Methods and Apparatus for Forming Multi-Layer Structures Using Adhered Masks

ABSTRACT

Numerous electrochemical fabrication methods and apparatus are provided for producing multi-layer structures (e.g. having meso-scale or micro-scale features) from a plurality of layers of deposited materials using adhered masks (e.g. formed from liquid photoresist or dry film), where two or more materials may be provided per layer where at least one of the materials is a structural material and one or more of any other materials may be a sacrificial material which will be removed after formation of the structure. Materials may comprise conductive materials that are electrodeposited or deposited in an electroless manner. In some embodiments special care is undertaken to ensure alignment between patterns formed on successive layers.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/479,638 (Microfabrica Docket No. P-US098-B-MF), filed Jun. 5, 2009.The '638 application is a divisional of U.S. patent application Ser. No.10/841,272 (US098-A), filed May 7, 2004 which in turn claims benefit ofU.S. Provisional Application Nos. 60/468,741 and 60/474,625 filed on May7, 2003 and May 29, 2003, respectively. These referenced applicationsare hereby incorporated herein by reference as is set forth in fullherein.

FIELD OF THE INVENTION

Embodiments of the invention relate generally to the field ofelectrochemical fabrication and the associated formation ofthree-dimensional structures (e.g. microscale or mesoscale structures).In particular, they relate to the formation of such structures usingpatterned masks that are temporarily adhered to substrates or topreviously formed deposits that may be used for performing selectivepatterning of or on the substrates or previously deposited material.

BACKGROUND OF THE INVENTION

A technique for forming three-dimensional structures (e.g. parts,components, devices, and the like) from a plurality of adhered layerswas invented by Adam L. Cohen and is known as ElectrochemicalFabrication. It is being commercially pursued by Microfabrica® Inc. ofVan Nuys, Calif. under the name EFAB®. This technique was described inU.S. Pat. No. 6,027,630, issued on Feb. 22, 2000. This electrochemicaldeposition technique allows the selective deposition of a material usinga unique masking technique that involves the use of a mask that includespatterned conformable material on a support structure that isindependent of the substrate onto which plating will occur. Whendesiring to perform an electrodeposition using the mask, the conformableportion of the mask is brought into contact with a substrate while inthe presence of a plating solution such that the contact of theconformable portion of the mask to the substrate inhibits deposition atselected locations. For convenience, these masks might be genericallycalled conformable contact masks; the masking technique may begenerically called a conformable contact mask plating process. Morespecifically, in the terminology of Microfabrica® Inc. of Van Nuys,Calif. such masks have come to be known as INSTANT MASKS™ and theprocess known as INSTANT MASKING or INSTANT MASK™ plating. Selectivedepositions using conformable contact mask plating may be used to formsingle layers of material or may be used to form multi-layer structures.The teachings of the '630 patent are hereby incorporated herein byreference as if set forth in full herein.

Since the filing of the patent application that led to the above notedpatent, various papers about conformable contact mask plating (i.e.INSTANT MASKING) and electrochemical fabrication have been published:

-   -   (1) A. Cohen, G. Zhang, F. Tseng, F. Mansfeld, U. Frodis and P.        Will, “EFAB: Batch production of functional, fully-dense metal        parts with micro-scale features”, Proc. 9th Solid Freeform        Fabrication, The University of Texas at Austin, p161, August        1998.    -   (2) A. Cohen, G. Zhang, F. Tseng, F. Mansfeld, U. Frodis and P.        Will, “EFAB: Rapid, Low-Cost Desktop Micromachining of High        Aspect Ratio True 3-D MEMS”, Proc. 12th IEEE Micro Electro        Mechanical Systems Workshop, IEEE, p244, January 1999.    -   (3) A. Cohen, “3-D Micromachining by Electrochemical        Fabrication”, Micromachine Devices, March 1999.    -   (4) G. Zhang, A. Cohen, U. Frodis, F. Tseng, F. Mansfeld, and P.        Will, “EFAB: Rapid Desktop Manufacturing of True 3-D        Microstructures”, Proc. 2nd International Conference on        Integrated MicroNanotechnology for Space Applications, The        Aerospace Co., April 1999.    -   (5) F. Tseng, U. Frodis, G. Zhang, A. Cohen, F. Mansfeld, and P.        Will, “EFAB: High Aspect Ratio, Arbitrary 3-D Metal        Microstructures using a Low-Cost Automated Batch Process”, 3rd        International Workshop on High Aspect Ratio MicroStructure        Technology (HARMST'99), June 1999.    -   (6) A. Cohen, U. Frodis, F. Tseng, G. Zhang, F. Mansfeld, and P.        Will, “EFAB: Low-Cost, Automated Electrochemical Batch        Fabrication of Arbitrary 3-D Microstructures”, Micromachining        and Microfabrication Process Technology, SPIE 1999 Symposium on        Micromachining and Microfabrication, September 1999.    -   (7) F. Tseng, G. Zhang, U. Frodis, A. Cohen, F. Mansfeld, and P.        Will, “EFAB: High Aspect Ratio, Arbitrary 3-D Metal        Microstructures using a Low-Cost Automated Batch Process”, MEMS        Symposium, ASME 1999 International Mechanical Engineering        Congress and Exposition, November, 1999.    -   (8) A. Cohen, “Electrochemical Fabrication (EFABTM)”, Chapter 19        of The MEMS Handbook, edited by Mohamed Gad-El-Hak, CRC Press,        2002.    -   (9) “Microfabrication—Rapid Prototyping's Killer Application”,        pages 1-5 of the Rapid Prototyping Report, CAD/CAM Publishing,        Inc., June 1999.

The disclosures of these nine publications are hereby incorporatedherein by reference as if set forth in full herein.

The electrochemical deposition process may be carried out in a number ofdifferent ways as set forth in the above patent and publications. In oneform, this process involves the execution of three separate operationsduring the formation of each layer of the structure that is to beformed:

-   -   1. Selectively depositing at least one material by        electrodeposition upon one or more desired regions of a        substrate.    -   2. Then, blanket depositing at least one additional material by        electrodeposition so that the additional deposit covers both the        regions that were previously selectively deposited onto, and the        regions of the substrate that did not receive any previously        applied selective depositions.    -   3. Finally, planarizing the materials deposited during the first        and second operations to produce a smoothed surface of a first        layer of desired thickness having at least one region containing        the at least one material and at least one region containing at        least the one additional material.

After formation of the first layer, one or more additional layers may beformed adjacent to the immediately preceding layer and adhered to thesmoothed surface of that preceding layer. These additional layers areformed by repeating the first through third operations one or more timeswherein the formation of each subsequent layer treats the previouslyformed layers and the initial substrate as a new and thickeningsubstrate.

Once the formation of all layers has been completed, at least a portionof at least one of the materials deposited is generally removed by anetching process to expose or release the three-dimensional structurethat was intended to be formed.

The preferred method of performing the selective electrodepositioninvolved in the first operation is by conformable contact mask plating.In this type of plating, one or more conformable contact (CC) masks arefirst formed. The CC masks include a support structure onto which apatterned conformable dielectric material is adhered or formed. Theconformable material for each mask is shaped in accordance with aparticular cross-section of material to be plated. At least one CC maskis needed for each unique cross-sectional pattern that is to be plated.

The support for a CC mask is typically a plate-like structure formed ofa metal that is to be selectively electroplated and from which materialto be plated will be dissolved. In this typical approach, the supportwill act as an anode in an electroplating process. In an alternativeapproach, the support may instead be a porous or otherwise perforatedmaterial through which deposition material will pass during anelectroplating operation on its way from a distal anode to a depositionsurface. In either approach, it is possible for CC masks to share acommon support, i.e. the patterns of conformable dielectric material forplating multiple layers of material may be located in different areas ofa single support structure. When a single support structure containsmultiple plating patterns, the entire structure is referred to as the CCmask while the individual plating masks may be referred to as“submasks”. In the present application such a distinction will be madeonly when relevant to a specific point being made.

In preparation for performing the selective deposition of the firstoperation, the conformable portion of the CC mask is placed inregistration with and pressed against a selected portion of thesubstrate (or onto a previously formed layer or onto a previouslydeposited portion of a layer) on which deposition is to occur. Thepressing together of the CC mask and substrate occur in such a way thatall openings, in the conformable portions of the CC mask contain platingsolution. The conformable material of the CC mask that contacts thesubstrate acts as a barrier to electrodeposition while the openings inthe CC mask that are filled with electroplating solution act as pathwaysfor transferring material from an anode (e.g. the CC mask support) tothe non-contacted portions of the substrate (which act as a cathodeduring the plating operation) when an appropriate potential and/orcurrent are supplied.

An example of a CC mask and CC mask plating are shown in FIGS. 1(a)-1(c). FIG. 1( a) shows a side view of a CC mask 508 consisting of aconformable or deformable (e.g. elastomeric) insulator 510 patterned onan anode 512. The anode has two functions. FIG. 1( a) also depicts asubstrate 506 separated from mask 508. One is as a supporting materialfor the patterned insulator 510 to maintain its integrity and alignmentsince the pattern may be topologically complex (e.g., involving isolated“islands” of insulator material). The other function is as an anode forthe electroplating operation. CC mask plating selectively depositsmaterial 522 onto a substrate 506 by simply pressing the insulatoragainst the substrate then electrodepositing material through apertures526 a and 526 b in the insulator as shown in FIG. 1( b). Afterdeposition, the CC mask is separated, preferably non-destructively, fromthe substrate 506 as shown in FIG. 1( c). The CC mask plating process isdistinct from a “through-mask” plating process in that in a through-maskplating process the separation of the masking material from thesubstrate would occur destructively. As with through-mask plating, CCmask plating deposits material selectively and simultaneously over theentire layer. The plated region may consist of one or more isolatedplating regions where these isolated plating regions may belong to asingle structure that is being formed or may belong to multiplestructures that are being formed simultaneously. In CC mask plating asindividual masks are not intentionally destroyed in the removal process,they may be usable in multiple plating operations.

Another example of a CC mask and CC mask plating is shown in FIGS. 1(d)-1(f). FIG. 1( d) shows an anode 512′ separated from a mask 508′ thatincludes a patterned conformable material 510′ and a support structure520. FIG. 1( d) also depicts substrate 506 separated from the mask 508′.FIG. 1( e) illustrates the mask 508′ being brought into contact with thesubstrate 506. FIG. 1( f) illustrates the deposit 522′ that results fromconducting a current from the anode 512′ to the substrate 506. FIG. 1(g) illustrates the deposit 522′ on substrate 506 after separation frommask 508′. In this example, an appropriate electrolyte is locatedbetween the substrate 506 and the anode 512′ and a current of ionscoming from one or both of the solution and the anode are conductedthrough the opening in the mask to the substrate where material isdeposited. This type of mask may be referred to as an anodeless INSTANTMASK™ (AIM) or as an anodeless conformable contact (ACC) mask.

Unlike through-mask plating, CC mask plating allows CC masks to beformed completely separate from the fabrication of the substrate onwhich plating is to occur (e.g. separate from a three-dimensional (3D)structure that is being formed). CC masks may be formed in a variety ofways, for example, a photolithographic process may be used. All maskscan be generated simultaneously, prior to structure fabrication ratherthan during it. This separation makes possible a simple, low-cost,automated, self-contained, and internally-clean “desktop factory” thatcan be installed almost anywhere to fabricate 3D structures, leaving anyrequired clean room processes, such as photolithography to be performedby service bureaus or the like.

An example of the electrochemical fabrication process discussed above isillustrated in FIGS. 2( a)-2(f). These figures show that the processinvolves deposition of a first material 502 which is a sacrificialmaterial and a second material 504 which is a structural material. TheCC mask 508, in this example, includes a patterned conformable material(e.g. an elastomeric dielectric material) 510 and a support 512 which ismade from deposition material 502. The conformal portion of the CC maskis pressed against substrate 506 with a plating solution 514 locatedwithin the openings 516 in the conformable material 510. An electriccurrent, from power supply 518, is then passed through the platingsolution 514 via (a) support 512 which doubles as an anode and (b)substrate 506 which doubles as a cathode. FIG. 2( a), illustrates thatthe passing of current causes material 502 within the plating solutionand material 502 from the anode 512 to be selectively transferred to andplated on the cathode 506. After electroplating the first depositionmaterial 502 onto the substrate 506 using CC mask 508, the CC mask 508is removed as shown in FIG. 2( b). FIG. 2( c) depicts the seconddeposition material 504 as having been blanket-deposited (i.e.non-selectively deposited) over the previously deposited firstdeposition material 502 as well as over the other portions of thesubstrate 506. The blanket deposition occurs by electroplating from ananode (not shown), composed of the second material, through anappropriate plating solution (not shown), and to the cathode/substrate506. The entire two-material layer is then planarized to achieve precisethickness and flatness as shown in FIG. 2( d). After repetition of thisprocess for all layers, the multi-layer structure 520 formed of thesecond material 504 (i.e. structural material) is embedded in firstmaterial 502 (i.e. sacrificial material) as shown in FIG. 2( e). Theembedded structure is etched to yield the desired device, i.e. structure520, as shown in FIG. 2( f).

Various components of an exemplary manual electrochemical fabricationsystem 532 are shown in FIGS. 3( a)-3(c). The system 532 consists ofseveral subsystems 534, 536, 538, and 540. The substrate holdingsubsystem 534 is depicted in the upper portions of each of FIGS. 3( a)to 3(c) and includes several components: (1) a carrier 548, (2) a metalsubstrate 506 onto which the layers are deposited, and (3) a linearslide 542 capable of moving the substrate 506 up and down relative tothe carrier 548 in response to drive force from actuator 544. Subsystem534 also includes an indicator 546 for measuring differences in verticalposition of the substrate which may be used in setting or determininglayer thicknesses and/or deposition thicknesses. The subsystem 534further includes feet 568 for carrier 548 which can be precisely mountedon subsystem 536.

The CC mask subsystem 536 shown in the lower portion of FIG. 3( a)includes several components: (1) a CC mask 508 that is actually made upof a number of CC masks (i.e. submasks) that share a commonsupport/anode 512, (2) precision X-stage 554, (3) precision Y-stage 556,(4) frame 572 on which the feet 568 of subsystem 534 can mount, and (5)a tank 558 for containing the electrolyte 516. Subsystems 534 and 536also include appropriate electrical connections (not shown) forconnecting to an appropriate power source for driving the CC maskingprocess.

The blanket deposition subsystem 538 is shown in the lower portion ofFIG. 3( b) and includes several components: (1) an anode 562, (2) anelectrolyte tank 564 for holding plating solution 566, and (3) frame 574on which the feet 568 of subsystem 534 may sit. Subsystem 538 alsoincludes appropriate electrical connections (not shown) for connectingthe anode to an appropriate power supply for driving the blanketdeposition process.

The planarization subsystem 540 is shown in the lower portion of FIG. 3(c) and includes a lapping plate 552 and associated motion and controlsystems (not shown) for planarizing the depositions.

In addition to teaching the use of CC masks for electrodepositionpurposes, the '630 patent also teaches that the CC masks may be placedagainst a substrate with the polarity of the voltage reversed andmaterial may thereby be selectively removed from the substrate. Itindicates that such removal processes can be used to selectively etch,engrave, and polish a substrate, e.g., a plaque.

The '630 patent further indicates that the electroplating methods andarticles disclosed therein allow fabrication of devices from thin layersof materials such as, e.g., metals, polymers, ceramics, andsemiconductor materials. It further indicates that although theelectroplating embodiments described therein have been described withrespect to the use of two metals, a variety of materials, e.g.,polymers, ceramics and semiconductor materials, and any number of metalscan be deposited either by the electroplating methods therein, or inseparate processes that occur throughout the electroplating method. Itindicates that a thin plating base can be deposited, e.g., bysputtering, over a deposit that is insufficiently conductive (e.g., aninsulating layer) so as to enable subsequent electroplating. It alsoindicates that multiple support materials (i.e. sacrificial materials)can be included in the electroplated element allowing selective removalof the support materials.

Another method for forming microstructures from electroplated metals(i.e. using electrochemical fabrication techniques) is taught in U.S.Pat. No. 5,190,637 to Henry Guckel, entitled “Formation ofMicrostructures by Multiple Level Deep X-ray Lithography withSacrificial Metal layers”. This patent teaches the formation of metalstructure utilizing mask exposures. A first layer of a primary metal iselectroplated onto an exposed plating base to fill a void in aphotoresist, the photoresist is then removed and a secondary metal iselectroplated over the first layer and over the plating base. Theexposed surface of the secondary metal is then machined down to a heightwhich exposes the first metal to produce a flat uniform surfaceextending across the both the primary and secondary metals. Formation ofa second layer may then begin by applying a photoresist layer over thefirst layer and then repeating the process used to produce the firstlayer. The process is then repeated until the entire structure is formedand the secondary metal is removed by etching. The photoresist is formedover the plating base or previous layer by casting and the voids in thephotoresist are formed by exposure of the photoresist through apatterned mask via X-rays or UV radiation.

Further teachings concerning the formation of microstructures fromelectroplated metals (i.e. using electrochemical fabrication techniques)is taught in U.S. Pat. No. 5,718,618 by Henry Guckel, entitled “Lappingand Polishing Method and Apparatus for Planarizing Photoresist and MetalMicrostructure Layers”. This patent teaches a method and apparatus forplanarizing photoresist and/or metal microstructure layers.Planarization is achieved by removing material from a workpiece bylapping using a diamond containing lapping slurry. A lapping machine isfurnished with a lapping plate made of a soft metal material. Thelapping plate is furnished with ridges of controlled height using adiamond conditioning ring with a specified grit size. Free diamonds in aliquid slurry are then sprayed onto the plate and embedded therein by asecond conditioning ring. After the lapping plate is conditioned, thepiece to be lapped is mounted on the lapping plate. A vacuum holdfixture or flat steel or glass mounting plate may be used. Duringlapping, additional diamond slurry is sprayed onto the lapping plate anddriven into the plate by a ceramic conditioning ring. The size ofdiamonds in the diamond slurry is selected to control the shear forcesapplied to the surface being lapped and to achieve a desired surfacefinish. Polishing, using a cloth covered hard metal polishing plate andloose diamond slurry, may be employed after lapping to provide a smoothoptical surface finish. The lapping and polishing method and apparatusdescribed may be used for z-dimension height control, re-planarization,and surface finishing of precise single or multiple levelphotoresist-metal layers, or of individual preformed photoresist sheetsor laminates thereof.

Further teachings concerning the formation of microstructures fromelectroplated metals is taught in U.S. Pat. Nos. 5,378,583, 5,496,668,and 5,576,147 by Henry Guckel, and each entitled “Formation ofMicrostructures Using a Preformed Photoresist Sheet”. These patentsteach the formation of microstructures using a preformed sheet ofphotoresist, such as polymethylmethacrylate (PMMA), which is strainfree, and that may be milled down before or after adherence to asubstrate to a desired thickness. The photoresist is patterned byexposure through a mask to radiation, such as X-rays, and developedusing a developer to remove the photoresist material which has beenrendered susceptible to the developer. Micrometal structures may beformed by electroplating metal into the areas from which the photoresisthas been removed. The photoresist itself may form usefulmicrostructures, and can be removed from the substrate by utilizing arelease layer between the substrate and the preformed sheet which can beremoved by a remover which does not affect the photoresist. Multiplelayers of patterned photoresist can be built up to allow complex threedimensional microstructures to be formed.

Further teachings concerning the formation of microstructures fromelectroplated metals (i.e. using electrochemical fabrication techniques)is taught in US patent (Another method for forming microstructures fromelectroplated metals (i.e. using electrochemical fabrication techniques)is taught in U.S. Pat. Nos. 5,866,281 and 5,908,719 by Henry Guckel,both entitled “Alignment Method for Multi-Level Deep X-Ray LithographyUtilizing Alignment Holes and Posts”. These patents teach a procedurefor achieving accurate alignment between an X-ray mask and a devicesubstrate for the fabrication of multi-layer microstructures. A firstphotoresist layer on the substrate is patterned by a first X-ray mask toinclude first alignment holes along with a first layer microstructurepattern. Mask photoresist layers are attached to second and subsequentmasks that are used to pattern additional photoresist layers attached tothe microstructure device substrate. The mask photoresist layers arepatterned to include mask alignment holes that correspond in geometry tothe first alignment holes in the first photoresist layer on the devicesubstrate. Alignment between a second mask and the first photoresistlayer is achieved by assembly of the second mask onto the firstphotoresist layer using alignment posts placed in the first alignmentholes in the first photoresist layer that penetrate into the maskalignment holes in the mask photoresist layers. The alignment procedureis particularly applicable to the fabrication of multi-layer metalmicrostructures using deep X-ray lithography and electroplating. Thealignment procedure may be extended to multiple photoresist layers andlarger device heights using spacer photoresist sheets between subsequentmasks and the first photoresist layer that are joined together usingalignment posts.

Even though electrochemical fabrication methods as taught and practicedto date, have greatly enhanced the capabilities of microfabrication, andin particular added greatly to the number of metal layers that can beincorporated into a structure, electrochemical fabrication can stillbenefit from improved methods and apparatus for forming multi-layerstructures.

SUMMARY OF THE DISCLOSURE

It is an object of some aspects of the invention to provide enhancedmasking materials for use in electrochemically fabricating multi-layerstructures.

It is an object of some aspects of the invention to provide enhancedtechniques for electrochemically fabricating multi-layer structures thatinclude more than two materials on at least some layers.

It is an object of some aspects of the invention to reduce costs ofelectrochemically fabricating multi-layer structures.

It is an object of some aspects of the invention to provide morereliable electrochemically fabricated multi-layer structures.

It is an object of some aspects of the invention to provideelectrochemically fabricated multi-layer structures having improvedstructural properties.

It is an object of some aspects of the invention to reduce thefabrication time of producing electrochemically fabricated multi-layerstructures.

Other objects and advantages of various aspects of the invention will beapparent to those of skill in the art upon review of the teachingsherein. The various aspects of the invention, set forth explicitlyherein or otherwise ascertained from the teachings herein, may addressany one of the above objects alone or in combination, or alternativelyit may not address any of the objects set forth above but insteadaddress some other object of the invention which may be ascertained fromthe teachings herein. It is not intended that all of these objects beaddressed by any single aspect of the invention even though that may bethe case with regard to some aspects.

In a first aspect of the invention a process for forming a multilayerthree-dimensional structure, comprising: (a) forming and adhering alayer of material to a substrate or previously formed layer; and (b)repeating the forming and adhering operation of (a) a plurality of timesto build up a three-dimensional structure from a plurality of adheredlayers, where successive layers are adhered to previously formed layers;wherein the formation of at least one layer comprises: (i) forming andadhering a desired pattern of masking material on the substrate orpreviously formed layer, wherein the patterning of the masking materialresults in at least one void in the material that exposes a portion ofthe substrate or of a previously formed layer; (ii) depositing aconductive material into the at least one void in the masking material;and wherein the masking material comprises a dry film photoresist.

In a second aspect of the invention a carrier for holding a substrate,the carrier including a carrier body being perforated by at least oneaperture formed through the carrier body, wherein the substrate isbonded to the carrier body by a material formed in the at least oneaperture.

In a third aspect of the invention a carrier for holding a substrateduring formation of at least one layer of material on the substrate, thecarrier including a carrier body having a fixed reference surface forcontrolling a thickness of the at least one layer of material formed onthe substrate.

In a fourth aspect of the invention a carrier for holding a substrateduring formation of one or more layers of material on the substrate, thecarrier including a carrier body having a surface that provides areference for measuring a thickness of the one or more layers ofmaterial formed on the substrate.

In a fifth aspect of the invention a system for electrodepositing layersof material on a substrate, the system including: an electrodepositiontank having electrodeposition bath therein; a carrier acting as a firstelectrode having a first polarity, the carrier having a carrier body towhich the substrate is electrically connected, the substrate beingimmersed in the electrodeposition tank; a second electrode having asecond polarity opposite from the first polarity, the second electrodebeing immersed in the electrodeposition tank; and a power sourceelectrically connected to the carrier and the second electrode such thatmaterial from the second electrode is electrodeposited onto thesubstrate through the electrodeposition bath.

In a sixth aspect of the invention a system for controlling thickness oflayers formed on a substrate, including: a carrier for holding thesubstrate during formation of one or more layers of material on thesubstrate, the carrier including a carrier body having a surface thatprovides a reference for measuring a thickness of the one or more layersof material formed on the substrate; and a planarization fixture forsupporting the carrier body during planarization of the one or morelayers of material, the planarization fixture having at least onesurface adapted to mate with the reference surface of the carrier bodysuch that surfaces of the one or more layers of material formed on thesubstrate are parallel to the reference surface after planarization.

In a seventh aspect of the invention a method for forming one or morelayers of material on a substrate, including providing a carrier forholding the substrate during formation of the one or more layers ofmaterial on the substrate, the carrier including a carrier body having asurface providing a reference for measuring a thickness of the one ormore layers of material formed on the substrate.

In an eighth aspect of the invention a method for forming one or morelayers of material on a layer formation surface of a substrate,including providing a carrier for holding the substrate during formationof the one or more layers, the carrier including a carrier body having asurface that is substantially coplanar with the layer formation surface.

In a ninth aspect of the invention an imaging system for targetalignment, including: a first imaging device for focusing on a firsttarget to produce a first image; a second imaging device for focusing ona second target to produce a second image; and means for comparing thefirst and second images to determine a degree of misalignment betweenthe first and second targets.

In a tenth aspect of the invention a method for aligning targets,including: providing a first imaging device for focusing on a firsttarget to produce a first image; providing a second imaging device forfocusing on a second target to produce a second image; and comparing thefirst and second images to determine a degree of misalignment betweenthe first and second targets.

In an eleventh aspect of the invention a method for determining apriority for forming a sacrificial material and a structural material ona substrate, including: (a) analyzing features to be formed on thesubstrate; (b) determining whether a feature to be formed on thesubstrate has a predefined characteristic; (c) determining whether afeature determined in (b) to have the predefined characteristic is apositive feature or a negative feature; (d) forming the structuralmaterial first if it is determined in (c) that the feature is a negativefeature; and (e) forming the sacrificial material first if it isdetermined in (c) that the feature is a positive feature.

In a twelfth aspect of the invention a method for forming both smallpositive and negative features in the same layer of a substrate,including: (a) depositing a first patternable mold material on thelayer; (b) patterning the first patternable mold material to form afirst pattern; (c) depositing a first material in the first patternformed in (b); (d) removing the first patternable mold material toexpose areas of the layer not having the first material depositedthereon; (e) depositing a second patternable mold material over thelayer; (f) patterning the second patternable mold material to form asecond pattern; (g) depositing a second material in the second patternformed in (f); (h) removing the second patternable mold material toexpose areas of the layer not having the first or second materialsdeposited thereon; (i) blanket depositing the first material over thesecond material and the exposed areas of the layer; and (j) planarizingthe layer.

In a thirteenth aspect of the invention a method for forming more thantwo materials on the same layer, including: (a) depositing a firstpatternable mold material on the layer; (b) patterning the firstpatternable mold material to form a first pattern; (c) depositing afirst material in the first pattern formed in (b); (d) removing thefirst patternable mold material to expose areas of the layer not havingthe first material deposited thereon; (e) depositing a secondpatternable mold material over the layer; (f) patterning the secondpatternable mold material to form a second pattern; (g) depositing asecond material in the second pattern formed in (f); (h) removing thesecond patternable mold material to expose areas of the layer not havingthe first or second materials deposited thereon; (i) blanket depositinga third material over the second material and the exposed areas of thelayer; and (j) planarizing the layer.

In a fourteenth aspect of the invention a method for forming more thantwo materials on the same layer wherein two or more different materialsare adjacent to each other, including: (a) depositing a firstpatternable mold material on the layer; (b) patterning the firstpatternable mold material to form a first pattern; (c) depositing afirst material in the first pattern formed in (b); (d) removing thefirst patternable mold material to expose areas of the layer not havingthe first material deposited thereon; (e) depositing a secondpatternable mold material over the layer; (f) patterning the secondpatternable mold material to form a second pattern, the second patternincluding an aperture adjacent to the first material and exposing a topportion of the first material; (g) depositing a second material in thesecond pattern formed in (f) and over the exposed top portion of thefirst material; (h) removing the second patternable mold material toexpose areas of the layer not having the first or second materialsdeposited thereon; (i) blanket depositing a third material over thefirst and second materials and over the exposed areas of the layer; and(j) planarizing the layer.

In a fifteenth aspect of the invention a method for forming more thantwo materials on the same layer wherein two or more different materialsare adjacent to each other, including: (a) depositing a firstpatternable mold material on the layer; (b) patterning the firstpatternable mold material to form a first pattern; (c) depositing afirst material in the first pattern formed in (b); (d) depositing asecond patternable mold material over the first material and the firstpatternable mold material; (e) patterning the first and secondpatternable mold materials to form a second pattern, the second patternincluding an aperture adjacent to the first material and exposing a topportion of the first material; (f) depositing a second material in thesecond pattern formed in (e) and over the exposed top portion of thefirst material; (g) removing the first and second patternable moldmaterials to expose areas of the layer not having the first or secondmaterials deposited thereon; (h) blanket depositing a third materialover the first and second materials and over the exposed areas of thelayer; and (i) planarizing the layer.

In a sixteenth aspect of the invention a method for forming more thantwo materials on the same layer wherein two or more different materialsare adjacent to each other, including: (a) depositing a patternable moldmaterial on the layer; (b) patterning the patternable mold material afirst time to form a first pattern; (c) depositing a first material inthe first pattern formed in (b); (d) patterning the patternable moldmaterial a second time to form a second pattern, the second patternincluding an aperture adjacent to the first material; (e) depositing asecond material in the second pattern formed in (d); (f) removing thepatternable mold material to expose areas of the layer not having thefirst or second materials deposited thereon; (g) blanket depositing athird material over the first and second materials and over the exposedareas of the layer; and (h) planarizing the layer.

In a seventeenth aspect of the invention a method for forming more thantwo materials on the same layer wherein two or more different materialsare adjacent to each other, including: (a) forming an ablatable materialon the layer; (b) ablating the ablatable material a first time to form afirst pattern; (c) depositing a first material in the first patternformed in (b); (d) ablating the ablatable material a second time to forma second pattern, the second pattern including an aperture adjacent tothe first material and exposing a top portion of the first material; (e)depositing a second material in the second pattern formed in (d) andover the exposed top portion of the first material; (f) removing theablatable material to expose areas of the layer not having the first orsecond materials deposited thereon; (g) blanket depositing a thirdmaterial over the first and second materials and over the exposed areasof the layer; and (h) planarizing the layer.

In an eighteenth aspect of the invention a method for forming more thantwo materials on the same layer wherein two or more different materialsare adjacent to each other, including: (a) depositing a firstpatternable mold material on the layer; (b) patterning the firstpatternable mold material to form a first pattern; (c) depositing afirst material in the first pattern formed in (b); (d) depositing asecond patternable mold material over the first material and the firstpatternable mold material; (e) patterning the first and secondpatternable mold materials to form a second pattern, the second patternincluding an aperture adjacent to the first material and exposing a topportion of the first material.

In a nineteenth aspect of the invention a method for preparing a layerhaving formed thereon a feature consisting of a first material fordeposition of a second material adjacent to the first material,including: (a) depositing a patternable mold material over the firstmaterial; and (b) patterning the patternable mold material to form anaperture adjacent to the first material, the aperture exposing a sideportion and a top portion of the first material.

In a twentieth aspect of the invention a method for forming an alignmenttarget on a substrate, including: forming a first patternable moldmaterial on the substrate; patterning the first patternable moldmaterial to form a first aperture; forming a first material in the firstaperture to form an alignment target within the first aperture; removingthe first patternable mold material; forming a second patternable moldmaterial on the substrate so as to cover the alignment target; andforming the second patternable mold material to form a second aperturewider than and fully enclosing the alignment target.

In a twenty-first aspect of the invention a method for forming analignment target, including: providing a substrate having anon-conductive surface; forming a conductive layer over thenon-conductive surface; and forming a target portion of the conductivelayer such that the target portion is electrically isolated from theremainder of the conductive layer by the non-conductive surface.

In a twenty-second aspect of the invention an alignment target formedfrom a conductive layer deposited on a non-conductive surface of asubstrate such that the alignment target is electrically isolated fromthe remainder of the conductive layer by the non-conductive surface.

In a twenty-third aspect of the invention a method for forming analignment target, including: providing a substrate; forming anon-conductive material on a portion of a surface of the substrate;forming a conductive layer over the non-conductive material; and forminga target portion of the conductive layer such that the target portion iselectrically isolated from the remainder of the conductive layer by thenon-conductive material.

In a twenty-fourth aspect of the invention a method for electroplating alayer of material on a substrate, including: forming a conductive layerover a non-conductive surface of the substrate; forming a target in theconductive layer such that the target is electrically isolated from theremainder of the conductive layer by the non-conductive surface of thesubstrate; and electroplating the layer of material over the conductivelayer such that the conductive layer is plated and the target isun-plated.

In a twenty-fifth aspect of the invention a method for patterning oddand even layers of patternable material formed sequentially on asubstrate, including: patterning the odd layers using first photomaskshaving a first layout of alignment shapes and new target shapes, thefirst layout having a first orientation relative to the substrate; andpatterning the even layers using second photomasks having a secondlayout of alignment shapes and new target shapes, the second layouthaving a second orientation relative to the substrate different from thefirst orientation.

In a twenty-sixth aspect of the invention a photomask used in patterninglayers on a substrate, the photomask including a plurality of patternsfor a corresponding plurality of layers to be patterned on thesubstrate, at least two of the plurality of patterns having orientationsdifferent from each other relative to an orientation of the substrate,each of the different orientations being alignable with the orientationof the substrate.

In a twenty-seventh aspect of the invention a method for selecting apatternable mold material used in patterning a layer formed on asubstrate, including: (a) analyzing geometrical characteristics offeatures to be formed on the layer; and (b) selecting a patternable moldmaterial for patterning the layer based on the results of the analysisperformed in (a).

In a twenty-eighth aspect of the invention a method for forming layerson a substrate, including: providing a first patternable mold materialof a first type to be used in forming a first layer on the substrate;and providing a second patternable mold material of a second type usedin forming a second layer on the substrate.

In a twenty-ninth aspect of the invention a template for carrying asubstrate having layers formed thereon, the template including an uppersurface with an aperture formed therein for receiving the substrate suchthat an uppermost layer formed on the substrate is substantially flushwith the upper surface.

In a thirtieth aspect of the invention a method for laminating layersformed on a substrate, including providing a template for carryingthrough a laminator a substrate having layers formed thereon to belaminated, the template including an upper surface with an apertureformed therein for receiving the substrate.

In a thirty-first aspect of the invention a method for laminating layersformed on a substrate using a laminator, including: (a) determining athermal mass of the layers formed on the substrate; and (b) adjustingparameters of the laminator based the thermal mass determined in (a).

In a thirty-second aspect of the invention a method for forming layerson a substrate, including: forming a first layer of a patternable moldmaterial on the substrate; forming at least one additional layer of thepatternable mold material on the first layer; and patterning the firstlayer and the at least one additional layer.

In a thirty-third aspect of the invention a method for forming layers ona substrate, including: forming a layer of dry film resist having afirst thickness on a substrate; and thinning the layer such that thelayer has a second thickness less than the first thickness.

In a thirty-fourth aspect of the invention a method for fabricating amulti-layer structure, including patterning at least one layer of themulti-layer structure using a dry film resist.

In a thirty-fifth aspect of the invention a method for fabricating aMicroelectromechanical System (MEMS), including patterning at least onelayer used to fabricate the Microelectromechanical System (MEMS) using adry film resist.

In a thirty-sixth aspect of the invention a method for forming on asurface a layer of material having an object incorporated therein, themethod including: forming a first layer of patternable mold material ona first surface; forming a first aperture in the first layer ofpatternable mold material for receiving an object; placing the object inthe first aperture; and forming a first material in the first aperturesuch that the first material encases the object.

In a thirty-seventh aspect of the invention a structure formed on asubstrate, including a plurality of layers of structural material formedone over another, at least one of the plurality of layers having anobject incorporated therein.

In a thirty-eighth aspect of the invention a structure, including: afirst layer of material formed on a substrate, the first layer ofmaterial having a first aperture formed therein; at least one objectheld loosely within the first aperture; and a second layer of materialformed over the first layer of material for securing the object in thefirst aperture.

In a thirty-ninth aspect of the invention a structure, including: afirst layer of material formed on a substrate, the first layer ofmaterial having a track formed therein; a plurality of objects heldloosely within the track; and a second layer of material formed over thefirst layer of material for securing the objects in the track.

In a fortieth aspect of the invention a method for forming on a surfacea layer of material for incorporating an object therein, including:forming a first patternable mold material on the surface; patterningapertures in the first patternable mold material; depositing a firstmaterial into the apertures to form at least two portions of the firstmaterial separated by the first patternable mold material; removing thefirst patternable mold material to form a cavity between the at leasttwo portions of the first material for receiving the object; forming asecond patternable mold material to provide a barrier against depositionof a second material into the cavity; depositing the second material;and removing the second patternable mold material.

In a forty-first aspect of the invention a method for forming astructure on a surface, including: building a plurality of layers on thesurface, the plurality of layers including both a structural materialand a sacrificial material; and after building the plurality of layers,removing the sacrificial material from the plurality of layers; whereinthe sacrificial material is a patternable mold material.

In a forty-second aspect of the invention a method for forming astructure on a surface, including: forming a first layer of patternablemold material; patterning first apertures in the first layer ofpatternable mold material; depositing a first structural material intothe first apertures; forming a second layer of patternable mold materialover the first layer of patternable mold material and the firststructural material; patterning second apertures into the second layerof patternable mold material; and depositing a second structuralmaterial into the second apertures.

In a forty-third aspect of the invention a method for forming astructure on a surface, including: forming a first layer of patternablemold material; patterning first apertures in the first layer ofpatternable mold material; depositing a first conductive material intothe first apertures; applying a coating of conductive particles over thefirst layer of patternable mold material; forming a second layer ofpatternable mold material; patterning second apertures in the secondlayer of patternable mold material to expose portions of the coating ofconductive particles and the first conductive material; and depositing asecond conductive material into the second apertures.

In a forty-fourth aspect of the invention a method for forming astructure on a surface, including: forming a first layer of patternablemold material; patterning first apertures in the first layer ofpatternable mold material; depositing a first conductive material intothe first apertures; forming a second layer of patternable moldmaterial; patterning second apertures in the second layer of patternablemold material to expose areas of the first layer of patternable moldmaterial and areas of the first conductive material; depositing acoating of conductive particles into the second apertures such that theyare secured in the exposed areas of the first layer of patternable moldmaterial; and depositing a second conductive material into the secondapertures.

In a forty-fifth aspect of the invention a method for forming astructure on a surface, including: forming a first layer of patternablemold material; patterning apertures in the first layer of patternablemold material; depositing a first metal into the apertures; removing thefirst layer of patternable mold material; and depositing a non-metallicconductive material such that the non-metallic conductive materialelectrically couples portions of the first metal to each other to form aplating base for plating a second metal.

In a forty-sixth aspect of the invention a method for forming astructure on a surface, including: forming a first layer of patternablemold material having conductive particles dispersed therein; and drivingthe conductive particles to an upper surface of the first layer ofpatternable mold material to form a plating surface for plating asubsequent layer of material.

In a forty-seventh aspect of the invention a method for formingstructures and dicing lanes on a substrate, including: forming a firstlayer of patternable mold material on a surface; patterning firstapertures in the first layer of patternable mold material; forming afirst material in the first apertures; and removing the first layer ofpatternable mold material to expose portions of the surface, a pluralityof the exposed portions of the surface functioning as dicing lanes.

In a forty-eighth aspect of the invention a method for forming an arrayof structures, including: forming a first layer of patternable moldmaterial on a surface; exposing the first layer of patternable moldmaterial using a first photomask to form a first pattern of soluble andinsoluble portions of the first layer of patternable mold material, thefirst pattern for forming an array of structures having a first numberof structures; and exposing the first pattern using a second photomaskdifferent from the first photomask to form a second pattern of solubleand insoluble portions of the first layer of patternable mold materialfrom the first pattern, the second pattern for forming an array ofstructures having a second number of structures different from the firstnumber of structures.

In a forty-ninth aspect of the invention a method for formingstructures, including: forming a first layer on a surface, the firstlayer including first portions of structural material and first portionsof sacrificial material; forming a second layer over the first layer,the second layer including second portions of structural material andsecond portions of sacrificial material, some of the second portions ofstructural material being formed over the first portions of structuralmaterial and others of the second portions of structural material beingformed over the first portions of sacrificial material; and removing thefirst and second portions of sacrificial material such that the secondportions of structural material being formed over the first portions ofsacrificial material are also removed.

In a fiftieth aspect of the invention a method for forming an array ofstructures, including exposing a layer of patternable mold materialusing a first photomask having a first pattern for forming an array ofstructures having a first number of structures and a second photomaskhaving a second pattern for forming an array of structures having asecond number of structures different from the first number ofstructures, the first and second photomasks being used simultaneously toexpose the first layer of patternable mold material.

In a fifty-first aspect of the invention a process for forming amultilayer three-dimensional structure, comprising: (a) forming andadhering a layer of material to a substrate or previously formed layer;and (b) repeating the forming and adhering operation of (a) a pluralityof times to build up a three-dimensional structure from a plurality ofadhered layers, where successive layers are adhered to previously formedlayers; wherein the formation of at least one layer comprises: (i)forming and adhering a desired pattern of masking material on thesubstrate or previously formed layer, wherein the patterning of themasking material results in at least one void in the material thatexposes a portion of the substrate or of a previously formed layer; (ii)depositing a conductive material into the at least one void in themasking material; and wherein the formation of the at least one layeradditionally comprises removing the masking material, depositing asecond material, and planarizing the deposited first and secondmaterials to a desired height.

In a fifty-second aspect of the invention a process for forming amultilayer three-dimensional structure, comprising: (a) forming andadhering a layer of material to a substrate or previously formed layer;and (b) repeating the forming and adhering operation of (a) a pluralityof times to build up a three-dimensional structure from a plurality ofadhered layers, where successive layers are adhered to previously formedlayers; wherein the formation of at least one layer comprises: (i)forming and adhering a desired pattern of masking material on thesubstrate or previously formed layer, wherein the patterning of themasking material results in at least one void in the material thatexposes a portion of the substrate or of a previously formed layer; (ii)depositing a conductive material into the at least one void in themasking material; and wherein the formation of the at least one layeradditionally comprises removing the masking material and depositing adielectric material, and wherein the formation of a subsequent layercomprises depositing a seed layer on at least a portion of the at leastone layer.

In a fifty-third aspect of the invention a process for forming amultilayer three-dimensional structure, comprising: (a) forming andadhering a layer of material to a substrate or previously formed layer;and (b) repeating the forming and adhering operation of (a) a pluralityof times to build up a three-dimensional structure from a plurality ofadhered layers, where successive layers are adhered to previously formedlayers; wherein the formation of at least one layer comprises: (i)forming and adhering a desired pattern of masking material on thesubstrate or previously formed layer, wherein the patterning of themasking material results in at least one void in the material thatexposes a portion of the substrate or of a previously formed layer; (ii)depositing a conductive material into the at least one void in themasking material; and wherein the formation of the at least one layeradditionally comprises depositing a seed layer on the substrate, orpreviously formed layer, which comprises only conductive material, priorto forming and adhering the mask material.

In a fifty-fourth aspect of the invention a process for forming amultilayer three-dimensional structure, comprising: (a) forming andadhering a layer of material to a substrate or previously formed layer;and (b) repeating the forming and adhering operation of (a) a pluralityof times to build up a three-dimensional structure from a plurality ofadhered layers, where successive layers are adhered to previously formedlayers; wherein the formation of at least one layer comprises: (i)forming and adhering a desired pattern of masking material on thesubstrate or previously formed layer, wherein the patterning of themasking material results in at least one void in the material thatexposes a portion of the substrate or of a previously formed layer; (ii)depositing a conductive material into the at least one void in themasking material; and wherein the at least one layer, after it iscompleted, comprises at least three different materials located indifferent lateral positions on the layer.

In a fifty-fifth aspect of the invention a process for forming amultilayer three-dimensional structure, comprising: (a) forming andadhering a layer of material to a substrate or previously formed layer;and (b) repeating the forming and adhering operation of (a) a pluralityof times to build up a three-dimensional structure from a plurality ofadhered layers, where successive layers are adhered to previously formedlayers; wherein the formation of at least one layer comprises: (i)forming and adhering a desired pattern of masking material on thesubstrate or previously formed layer, wherein the patterning of themasking material results in at least one void in the material thatexposes a portion of the substrate or of a previously formed layer; (ii)depositing a conductive material into the at least one void in themasking material; and wherein the formation of the at least one layeradditionally comprises optically aligning a position of the patterningof the dielectric material by using a focused image of an alignment markthat is located at on least one of (1) the substrate, (2) a carrier onwhich the substrate sits, or (3) previously deposited material that islocated on the substrate.

Further aspects of the invention will be understood by those of skill inthe art upon reviewing the teachings herein. Other aspects of theinvention may involve combinations of the above noted aspects of theinvention and/or addition of various features of one or moreembodiments. Other aspects of the invention may involve apparatus thatare configured to implement one or more of the above method aspects ofthe invention. These other aspects of the invention may provide variouscombinations of the aspects presented above as well as provide otherconfigurations, structures, functional relationships, and processes thathave not been specifically set forth above.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1( a)-1(c) schematically depict side views of various stages of aCC mask plating process, while FIGS. 1( d)-(g) schematically depict aside views of various stages of a CC mask plating process using adifferent type of CC mask.

FIGS. 2( a)-2(f) schematically depict side views of various stages of anelectrochemical fabrication process as applied to the formation of aparticular structure where a sacrificial material is selectivelydeposited while a structural material is blanket deposited.

FIGS. 3( a)-3(c) schematically depict side views of various examplesubassemblies that may be used in manually implementing theelectrochemical fabrication method depicted in FIGS. 2( a)-2(f).

FIGS. 4( a)-4(i) schematically depict the formation of a first layer ofa structure using adhered mask plating where the blanket deposition of asecond material overlays both the openings between deposition locationsof a first material and the first material itself.

FIGS. 5( a)-5(ii) illustrate an apparatus and method, according to anembodiment of the invention where a carrier is used to hold a substrateduring at least part of the process of forming a three-dimensionalstructure.

FIGS. 6( a)-6(c) depict side views of an alternative carrier bodyconfiguration that allows interlocked bonding between the carrier and asubstrate.

FIGS. 7( a)-7(b) each depict a top, side, and perspective view of acarrier body, respectively, having a conical shaped aperture or anelongated v-shaped aperture.

FIG. 8 depicts a side view of rollers of a dry film laminator along witha sheet of dry film that is wrapped around one of the rollers and asubstrate that will be feed between the rollers.

FIGS. 9( a) and 9(b) depict perspective view of circular substrates andrectangular templates for holding the substrates when being feed into alaminator.

FIGS. 10( a)-10(b) depict sectional side views of the substrate andtemplate of FIG. 9( b) along with shims that may be located beneath thesubstrate to ensure appropriate matching of the upper surfaces of thesubstrate and the template.

FIGS. 11( a)-11(e) depict side views of various stages of an exampleprocess where multiple layers of photoresist are added to a substrateprior to patterning them.

FIGS. 12( a)-12(b) depict, respectively, examples of a small positivefeature and a small negative feature resulting from a selectivedeposition of material.

FIG. 13 depicts a side view of a narrow feature that exists in a firstdeposited material into which a blanket deposited material does notcomplete fill as a result, at least in part, of the aspect ratio (i.e.height/width) of the feature.

FIGS. 14( a)-14(h) depict schematic side views of various states of aprocess for forming a narrow positive feature such as that shown in FIG.12( a).

FIGS. 15( a)-15(e) depict schematic side views of various states of aprocess for forming a narrow negative feature such as that shown in FIG.12( b).

FIG. 16 provides a flowchart of a process for determining priority ofdeposition based on the existence of certain features on a layer.

FIGS. 17( a)-17(g) depict schematic side views of various states of aprocess for forming a layer containing both narrow negative and narrowpositive features where the patternable mold material cannot generallyproduce small features of both types.

FIGS. 18( a)-18(k) depicts a process for depositing more than twomaterials on a single layer.

FIGS. 19( a)-19(k) depicts a process of a first exemplary embodiment fordepositing more than two materials on a single layer where two or moredifferent materials are adjacent to each other.

FIGS. 20( a)-20(j) depicts a process of a second exemplary embodimentfor depositing more than two materials on a single layer where two ormore different materials are adjacent to each other.

FIGS. 21( a)-21(i) depicts a process of a third exemplary embodiment fordepositing more than two materials on a single layer where two or moredifferent materials are adjacent to each other.

FIGS. 22( a)-22(i) depicts a process of a fourth exemplary embodimentfor depositing more than two materials on a single layer where two ormore different materials may be adjacent to each other.

FIGS. 23( a)-23(b) depict, respectively, side views of structures thatexpand and contract with the formation of successive layers forming atleast part of a multi-layer structure.

FIGS. 24( a)-24(g) depict schematic side views of various states of aprocess for forming an expanding structure, such as that shown in FIG.23( a), where photoresist is exposed in a plurality of layer operationsbut where development occurs only after exposure of multiple layers ofphotoresist occur and then back filling of the created void with astructural material occurs.

FIGS. 25( a)-25(g) illustrate an embodiment of a process for forming acontracting structure like that shown in FIG. 23( b).

FIG. 26 depicts a side view of a plurality of offset layers.

FIG. 27 provides a flowchart of a process for analyzing features on alayer to determine if a seed layer needs to be deposited.

FIGS. 28( a)-28(b) provide side views of two operations involved in anembodiment that uses backside alignment to ensure registration ofpatterning masks

FIGS. 29( a)-29(x) depict various stages of an embodiment of theinvention where alignment targets may be formed by electrodepositingmaterial.

FIGS. 30( a)-30(r) depict various stages of an embodiment of theinvention where alignment targets are formed in an adhesion layer and/orin a seed layer.

FIG. 31 shows a top view of a substrate, layer, and alignment targetsaccording to an embodiment of the invention.

FIGS. 32( a)-32(c) show examples, respectively, of an alignment targetthat may be located on a previous layer, an alignment target that may belocated on an alignment mask, and an overlaying of the two.

FIGS. 33( a)-33(d) depicts a series of mask and layer alignment targetsthat may be used on alternating layers according to some embodiments ofthe invention.

FIGS. 34( a)-34(b) depict a substrate, FIG. 34( a), having a singlequadrant on which useful structures will be formed and a mask, FIG. 34(b), having differently oriented patterns in each of four quadrants, suchthat upon each 90° rotation of the mask a different portion of thephotomask may be used in patterning the substrate which may reduce thenet number of photomasks needed to produce small quantities ofstructures.

FIGS. 35( a)-35(b) depict how substrate and mask alignment targets maybe aligned upon rotation according to some embodiments of the invention.

FIGS. 36( a)-36(d), schematically depict side views of variousrelationships between a carrier and a substrate that may be used in someembodiments of the invention.

FIGS. 37( a)-37(p) show a process for incorporating objects withinlayers formed on a substrate.

FIGS. 38( a)-38(p) show another embodiment of the invention forincorporating foreign objects within layers formed on a substrate.

FIG. 39 shows a top view of a step in the formation of a ball bearingstructure formed according to some embodiments of the invention.

FIG. 40 shows a completed ball bearing structure formed according tosome embodiments of the invention.

FIGS. 41( a)-41(k) show another embodiment of the invention forincorporating foreign objects within layers formed on a substrate.

FIGS. 42( a)-42(p) provide a schematic illustration of various stages ofa process for forming multi-layer structures where the patternable moldmaterial is used as the sacrificial material.

FIGS. 43( a)-43(r) show an alternative embodiment for using patternablemold material as the sacrificial material.

FIGS. 44( a)-44(i) show another alternative embodiment for usingpatternable mold material as the sacrificial material.

FIGS. 45( a)-45(m) show an embodiment of the invention for buildinglayers on large substrates in such a manner as to minimize stresses to alarge substrate that may result from deposited materials.

FIGS. 46( a)-46(q) show an embodiment of the invention for fabricatingcustomized arrays of devices without needing to use an entirely new setof photomasks for each customized array configuration.

FIGS. 47( a)-47(q) show another embodiment of the invention forfabricating customized arrays of devices without needing to use adifferent set of photomasks for each customized array configuration.

FIGS. 48( a)-48(b) show a sample multi-element structure which is formedusing a structural material and a sacrificial material and where thesacrificial material has been removed as shown in FIG. 48( b).

FIGS. 49( a)-49(b) show a sample multi-element structure whereindividual elements have different lengths before and after removal ofsacrificial material.

FIGS. 50( a)-50(d) show two sample multi-element structures whereindividual elements have different lengths before and after removal ofsacrificial material and where a second substrate is added to the buildso as to retain elements of the second structure that would otherwisehave been lost.

FIGS. 51( a)-51(b) illustrate an embodiment similar to that of FIGS. 49(a) and 49(b) with the exception structural material elements that are tobe removed are held together by a bridging structure.

FIGS. 52( a)-52(g) show an embodiment of the invention forpre-patterning a patternable mold material on a temporary substratebefore using the temporary substrate to form a pattern for depositingother materials on a separate substrate.

FIGS. 53( a)-53(f) show another embodiment of the invention fortransferring a pattern from a temporary substrate to a build substrate.

FIGS. 54( a)-54(f) show another embodiment of the invention fortransferring a pattern from a temporary substrate to a build substrate.

FIGS. 55( a)-55(i) show an embodiment of the invention for depositingmore than one material in an aperture formed in a patternable moldmaterial such that a layered deposit of materials are formed on a singlelayer.

FIGS. 56( a)-56(i) show an alternative embodiment of the invention fordepositing more than one material in an aperture formed in a patternablemold material such that a layered deposit of materials are formed on asingle layer.

FIGS. 57( a)-57(g) show an embodiment of the invention for using apatternable mold material to perform a patterned etch.

FIGS. 58( a)-58(j) show an embodiment of the invention for using apatternable mold material both to etch a pattern in a first material andto plate a second material in the etched pattern.

FIGS. 59( a)-59(i) show a further embodiment of the invention forforming a target on a substrate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1( a)-1(g), 2(a)-2(f), and 3(a)-3(c) illustrate various featuresof one form of electrochemical fabrication that are known. Otherelectrochemical fabrication techniques are set forth in the '630 patentreferenced above, in the various previously incorporated publications,in various other patents and patent applications incorporated herein byreference, still others may be derived from combinations of variousapproaches described in these publications, patents, and applications,or are otherwise known or ascertainable by those of skill in the artfrom the teachings set forth herein. All of these techniques may becombined with those of the invention explicitly set forth herein toyield enhanced embodiments. Still other embodiments may be derived fromcombinations of the various embodiments explicitly set forth herein.

FIGS. 4( a)-4(i) illustrate various stages in the formation of amulti-layer three-dimensional structure formed using a fabricationprocess that involves the deposition of first and second metals on alayer-by-layer basis so as to build up the structure from a plurality ofadhered layers. In some embodiments, the first and/or second materialsmay be electrodeposited (e.g. using electroplating or electrophoreticdeposition) while in some embodiments, the one or both of the materialsmay be deposited via an electroless deposition, via thermal spraying,sputtering, spreading, and the like. A first metal is deposited toselected locations via openings in a mask that is adhered to thesubstrate (which may include previously deposited materials or layers)while a second metal is deposited so as to fill voids in the layerlocated between locations of the first metal. Successive layers aredeposited on immediately preceding layers to build up desired structuresfrom multiple adhered layers.

In FIG. 4( a), a side view of a substrate 582 is shown, onto whichpatternable photoresist 584 (i.e. a patternable mold material) isapplied as shown in FIG. 4( b). The photoresist may be supplied andapplied in the form of a liquid or in the form of a dry film.Photoresists may be of the negative or positive types. In FIG. 4( c), apattern of resist is shown that results from the curing (if applied as aliquid) or adhering (if applied as a dry film), exposing (e.g. via UVradiation applied through a photomask), and developing of the resist.The patterning of the photoresist 584 results in openings or apertures92(a)-92(c) extending from a surface 586 of the photoresist through thethickness of the photoresist to surface 588 of the substrate 582.

In FIG. 4( d), a metal 594 (e.g. copper, silver, an alloy of copper, orthe like) is shown as having been deposited (e.g. electroplated) intothe openings 592(a)-592(c). In FIG. 4( e), the photoresist has beenremoved (i.e. chemically stripped) from the substrate to expose regionsof the substrate 582 which are not covered with the first metal 594. InFIG. 4( f), a second metal 596 (e.g., nickel, gold, tin, zinc, an alloyof nickel, or the like) is shown as having been blanket deposited (e.g.electroplated) over the entire exposed portions of the substrate 582(which is conductive) and over the first metal 594 (which is alsoconductive). FIG. 4( g) depicts the completed first layer of thestructure which has resulted from the planarization of the first andsecond metals down to a height that exposes the first metal and sets athickness for the first layer. The planarization operations may also setthe flatness of the formed layer and its surface finish.

FIG. 4( h) shows an example of the result of repeating the process stepsshown in FIGS. 4( b)-4(g) several times, with a different maskingpattern on each layer, to form a multi-layer structure. Each layerincludes two metals. For most applications, one of these metals isremoved as shown in FIG. 4( i) to yield a desired 3-D structure 598(e.g. component or device).

In some alternative embodiments, as will be discussed herein later, morethan two materials may be used. In such embodiments, each material maybe a metal, or some of them may be dielectrics. In various embodiments,one or more of the materials used in building up layers of the structuremay be a structural material (i.e. a material that will form part of thestructure itself) while one or more of the other materials may be asacrificial material (i.e. a material that will be removed prior toputting the structure (e.g. object, device, or component) to itsintended use.

Various embodiments of some aspects of the invention are directed toformation of three-dimensional structures from materials some of whichmay be electrodeposited. Some of these structures may be formed form asingle layer of one or more deposited materials while others are formedfrom a plurality of layers of deposited materials (e.g. 2 or morelayers, more preferably five or more layers, and most preferably ten ormore layers). In some embodiments structures having features positionedwith micron level precision and minimum features size on the order oftens of microns are to be formed. In other embodiments structures withless precise feature placement and/or larger minimum features may beformed. In still other embodiments, higher precision and smaller minimumfeature sizes may be desirable.

Various embodiments to be discussed herein after may be focusedprimarily on a particular type of masking technique for selectivepatterning of deposited materials. However, each embodiment may havealternatives that are implementable with other patterning techniques.For example, some embodiments may have alternatives that may use contactmasks and contact masking operations, such as conformable contact masksas described above, or non-conformable masks and masking operations(i.e. masks and operations based on masks whose contact surfaces are notsignificantly conformable). Other alternatives may make use of proximitymasks and masking operations (i.e. operations that use masks that atleast partially selectively shield a substrate by their proximity to thesubstrate even if contact is not made). Still other alternatives maymake use of various types of adhered masks and masking operations (masksand operations that use masks that are adhered to a substrate onto whichselective deposition or etching is to occur as opposed to only beingcontacted to it). Adhered masks may be formed in a number of waysincluding, for example (1) by application of a photoresist, selectiveexposure of the photoresist, and then development of the photoresist,(2) selective transfer of pre-patterned masking material, and/or (3)direct formation of masks from computer controlled depositions ofmaterial. Selective patterning using masks may occur by depositing aselected material into voids or openings in the masks or it occur byselectively etching a surface of an already deposited material using themask. In other applications, selective patterning may not involve asignificant height of deposition of material or significant depth ofetching of material but instead may involve treating a surface in aselective manner, e.g. selective microetching of a surface (e.g. toimprove adhesion between it and a material), selective oxidization of asurface (e.g. to change its conductivity), selective chemical treatmentof a surface (e.g. in preparation for an electroless deposition), andthe like.

FIGS. 5( a)-(ii) illustrate schematic side views of the states of theprocess and apparatus components involved in forming a sample structureaccording to a first embodiment of the invention. In this embodiment, acarrier is provided for carrying a substrate on which layers of materialwill be formed during fabrication of a structure.

FIGS. 36( a)-(d), schematically depict side views of variousrelationships between a carrier and a substrate that may be used in someembodiments of the invention. FIG. 36( a) depicts a substrate without acarrier and thus indicates that in some embodiments of the invention, asubstrate 192 may be used without a carrier. FIGS. 36( b)-36(c) depictsome other relationships that may exist in other embodiments. In someembodiments a carrier 194 may have the same size as the substrate 192,as shown in FIG. 36( b). Other embodiments may use a carrier 196 that islarger than the substrate 192, as shown in FIG. 36( c). Still otherembodiments, may be use or include a carrier 198 that has a recess forreceiving substrate 192, as shown in FIG. 36( d).

Turning back to FIG. 5( a), a carrier 1 may include a carrier body 2having a highly planar surface 3. Carrier 1 may further include two ormore alignment target inserts 5 covered by removable protective covers7. Carrier body 2 may further include pressing means 9 for applyingpressure to a substrate 25 as shown in FIG. 5( c). According to someembodiments of the invention, the pressing means 109 may be any suitablemeans for applying pressure such as, but not limited to, one or moresprings, as shown in FIG. 5( a), one or more air cylinders, one or moreinflatable bladders, and the like. According to some other embodiments,the weight of substrate 125 may be sufficient to make use of a pressingmeans 9 unnecessary.

According to some embodiments of the invention, the carrier 1 mayfurther include contacting means 11 for making electrical contact withconductive substrates. The contacting means 11 may be any suitable meansfor making electrical contact such as, but not limited to, one or moresprings, as shown in FIG. 5( a), one or more ‘fuzz buttons’, one or more‘pogo pins’, and the like. Carrier 1 may further include damming means13 (for example, an elastomeric or conformable gasket). Furthermore,carrier 1 may include holes 15 for use in the eventual removal ofsubstrate 25 and to serve as reservoirs or risers for adhesive material23 as shown in FIG. 5( b), and heating elements 17 preferably in closeproximity to holes 15. The carrier 1 may further include a carrieridentification device 19 (such as, but not limited to, a bar code labelor radio frequency identification tag (RF ID tag). The carrieridentification device 19, in addition to or alternatively to identifyingthe carrier or substrate, may encode a partial or complete processsequence for a particular substrate, for example indicating type ofoperations to perform and operations already performed. For example, asequence of operations may be readable from an RF ID tag 19 along withan indication as to which operations have been completed and anycomments associated with them. In other words, this RF ID tag may notonly act as an identification tag but also as a production traveler thataccompanies the structure as it is being formed and indicates the stateof the process and next operations to perform.

Referring to FIG. 5( a), the carrier 1 is shown without substrate 25. Asshown in FIG. 5( b), according to some embodiments of the invention,meltable adhesive material 23 has been applied to fill holes 15 beforesubstrate 25 is loaded into the carrier. Material 23 should be extremelyrigid after solidification, preventing any relative motion of substrate25 and carrier body 2. Material 23 should also be removable, forexample, by melting or chemical dissolution. Material 23 shouldwithstand multiple cycles of temperature cycling that substrate 25 maybe exposed to while being coated with photoresist, being immersed inelectrodeposition baths, and the like. Suitable meltable adhesivematerials include, but are not limited to, a mounting wax such asCrystalBond™ 509 made by Aremco Products of Valley Cottage, N.Y. andStaystik™ 571 made by Cookson Electronics of Alpharetta, Ga.

Heating elements 17 are preferably activated in order to facilitate thematerial 23 filling operation. Removable film 21 has been attached tothe bottom of carrier 1. Film 21 may be, for example, wafer dicing tape.The flow of material 23 is limited by film 21 and by damming means 13,the latter preventing material 23 substantially from reaching contactingmeans 11 (which if material 23 is an insulator might impair electricalcontact between contacting means 11 and substrate 25). As depicted,damming means 13 also prevents material 23 from reaching and interferingwith the operation of pressing means 9.

Referring to FIG. 5( c), substrate 25—onto which one or more multi-layerstructures is to be fabricated—has been placed into carrier 1. In someembodiments carrier 1 includes a recess or pocket (as shown) forreceiving substrate 25 such that the top surface 28 of substrate 25 maybe made parallel and coplanar (i.e., flush) with the planar surface 3 ofthe carrier 1 (see FIG. 5( f)). Substrate 25 may be covered with a thinremovable film 27 preferably of uniform thickness (for example, waferdicing tape). In FIG. 5( d), carrier 1 and substrate 25 have beeninverted and placed on planar surface 29 (for example, a granite surfaceplate) with film 27 between substrate 25 and surface 29. Pressure isapplied to carrier 1 (if its own weight is insufficient) to presssubstrate 25 via film 27 against pressing means 9 so that top surface 28of substrate 25 is forced to be coplanar with planar surface 3 ofcarrier 1. Also as may be seen in FIG. 5( d), film 21 has been removed(this may be done after the step shown in FIG. 5( b)).

In FIG. 5( e), material 23 has been melted by activation of heatingelements 17, causing material 23 to flow and fill gaps, e.g. to fill gap30 of FIG. 5( d)) between substrate 25 and carrier 1, and causingsubstrate 25 to become rigidly adhered to carrier 1 when material 23 isallowed to cool and solidify. According to other embodiments, heatingelements 17 may be omitted and the entire assembly may be placed in anoven, for example, in order to melt material 23. In FIG. 5( f), film 27has been removed, leaving material 23 substantially co-planar withsurface 3.

Other embodiments of the invention may use other methods for securingthe substrate 25 to the carrier. For example, according to someembodiments, a low melting point solder may be used to secure substrate25 to carrier 1. According to one embodiment, an indium-based solder maybe used. The solder may be applied, for example, as a thin foil placedbetween the substrate 25 and the carrier 1 and subsequently heated (forexample, in an oven) to melt the thin foil. Alternatively, the soldermay be plated onto one or more surfaces. In some embodiments, a layer ofmetal (for example, gold) may be applied to the one or more surfaces toallow the surfaces to be soldered. In the case of using a conductivebonding material, it may be possible to remove damming means 13, as thesolder may be made to flow around pressing means 9 and prior topressing, the solder may be made flowable then pressing made to occursuch that pressing means and planar surface 9 bring carrier surface 3and substrate surface 28 flush, the solder, or other conductive bondingmaterial, may then be allowed to solidify locking the substrate 25 andcarrier 1 into fixed positions relative to one another.

Referring to FIGS. 6( a)-(c), according to other embodiments, carrier 1may include apertures formed through the carrier body 2 that may befilled with, for example, a plated or melted metal such that thesubstrate 25 may be mounted to the carrier body 2 and secured due to theadhesion of the plated or melted metal to the substrate 25 and/or due tomechanical interlocking after the plated or melted metal has solidified.

A cross section of carrier body 2 is shown in FIG. 6( a). As shown,carrier body 2 has tapered apertures 26 in several places extending fromsurface 3 of carrier body 2 through the carrier body to surface 105.Also shown in FIG. 6( a) is substrate 25 before attachment to carrierbody 2. According to some embodiments of the invention, substrate 25 maybe either a metal substrate or may be coated with metal on a leastsurface 101 such that metal may be plated onto surface 101. In addition,according to some embodiments where carrier body 2 is not metal,surfaces 107 may also be coated with metal (e.g. by sputtering) suchthat metal may be plated onto surfaces 107.

As shown in FIG. 6( b), while surface 101 of substrate 25 is heldagainst carrier body 2, material 102 is plated or melted such that it atleast partially fills apertures 26 and makes contact with surface 101and surfaces 107. When material 102 is deposited or solidifies it formsa good bond with surfaces 101 of substrate 25 and/or surfaces 107 ofcarrier body 2. According to some embodiments, surfaces 101 and surfaces107 may be roughened to enhance adhesion.

In addition to the bonding of the material 102 to surface 101 and/orsurfaces 107 as a result of plating or melting material 102 intoapertures 26, some embodiments of the invention also advantageouslyprovide a strong mechanical bond as a result of the geometrical shape ofthe apertures 26. FIG. 6( c) shows an example of the mechanical bond.The downward and sideways pointing arrows shown in FIG. 6( c) representa force that potentially could cause movement or separation of substrate25 relative to carrier body 2. The upward pointing arrows represent boththe bond formed between material 102 and surface 101 and the mechanicalbond resulting from the dovetail joint-like configuration formed bymaterial 102 (the tenon of the dovetail joint) and carrier body 2 (themortise of the dovetail joint). Due to the increased strength of thebond between substrate 25 and carrier body 2 achieved by embodiments ofthe invention, substrate 25 becomes more rigidly adhered to carrier 1.

A top view (looking toward surface 3) and a side cross-section view ofcarrier body 2, according to some embodiments of the invention, areshown in FIG. 7( a). The top view is shown in the upper portion of theFIG. 7( a) while the side view is shown in the lower portion of FIG. 7(a). In FIG. 7( a), apertures 26 have a conical shape similar to thatshown in FIG. 6( a)-(b) such that the dovetail joint-like configurationdescribed above may be achieved. Also shown in FIG. 7( a) is aperspective view of one of apertures 26 (shown on the right side of thefigure).

According to some embodiments of the invention, apertures 26 may haveany suitable geometric shape that provides a strong mechanical bondbetween carrier body 2 and substrate 25 after material 102 is formed inthe apertures. Some preferred embodiments of the invention use areentrant geometry, as shown in FIG. 7( a). FIG. 7( b) shows a top view(upper most portion of the figure), looking toward surface 3, and a sidesection view of carrier body 2 (lower-most portion of the figure, and aperspective view in the right most portion of the figure. As an exampleof an additional suitable reentrant geometric shape, FIG. 7( b) shows anaperture 26 having a v-shaped bar shape. As shown in the side view, thedovetail joint-like configuration described above may be achieved withthe v-shaped bar.

According to yet other embodiments, the aperture may have other suitableshapes. For example, the aperture may have a diameter or width atsurface 105 that is smaller than a diameter or width of the aperture atsurface 3, but wherein the shape of the aperture is not the smoothlytapered shape shown in FIG. 7( a). For example, a large portion of theaperture may have substantially vertical walls and a smaller portionthat widen or narrow as they approach surface 105 and/or surface 3,respectively.

If adhesion bonding of material 102 to surface 101 and/or surfaces 107is sufficient, then in some cases there is no need for a mechanical bondsuch as that provided by the reentrant or other geometrical shapesformed by material 102 and carrier body 2. Thus, in some embodiments,apertures 26 may have, for example, vertical walls. On the other hand,in embodiments where a mechanical bond is provided, the adhesive bondingof the material 102 to surface 101 and/or surfaces 107 may beunnecessary. Still other embodiments may use both types of bonding.

A build 103 of material layers may then be added to surface 28 ofsubstrate 25 during the electrodeposition process, as shown in FIG. 6(b). After the electrodeposition process, substrate 25 may be separatedfrom carrier body 2 by removing material 102. Material 102 may beremoved, for example, by dissolving, melting, chemically etching orelectro-chemically etching material 102 away. According to somepreferred embodiments of the invention, material 102 may be nickel orcopper. However, material 102 may also be a low temperature metal suchas indium, tin, or tin-lead. In still other embodiments, material 102may be a wax-like material, a thermal polymer, or even a thermoset orphotocurable polymer that may be eventually be removed, e.g. by burningit out. According to some embodiments, material 102 may be the same asthe sacrificial material used in the build, such that it may be removed(and the carrier 1 released) during the process for removing thesacrificial material. In some embodiments where the sacrificial materialis used as material 102, it may be undesirable to remove material 102while the sacrificial material is removed. In that case, material 102may be masked during, for example, an etching process for removing thesacrificial material.

In order to avoid distortion of the bond between carrier 1 and substrate25 due to mismatched coefficients of thermal expansion (CTE), someembodiments of the invention may substantially match the CTE of thematerials used to form the carrier 1 and the substrate 25. For example,if substrate 25 is formed from a metal, carrier 1 may also be formedfrom a metal. If, on the other hand, substrate 25 is formed from aceramic or polymer, carrier 1 may be also be formed from a ceramic orpolymer, respectively. In some embodiments, the adhesive materialsand/or plating materials used to bond the carrier 1 to the substrate 25may also be chosen to have a suitable CTE, i.e., if carrier 1 andsubstrate 25 are formed from metal, the adhesive may also be a metal.

In some embodiments, the adhesive may be chosen to allow for a mismatchof the CTEs of carrier 1 and substrate 25, i.e., when one of the carrier1 or the substrate 25 expands more than the other, the adhesive willmaintain its bond between the two. In some embodiments, the adhesive maybe a conformable material or an elastomeric material. The CTE of thematerial 102 may also be matched to the CTE of the substrate and thematerials used to form the carrier 1, or may be chosen to allow for amismatch of the CTEs of carrier 1 and substrate 25 in embodimentswherein the carrier 1 has apertures as described above. If for example,the substrate and carrier are made of metals, material 102 may take theform of a glass (lower CTE) filled polymer (higher CTE) such that theCTE of the combination more closely matches that of the metals

According to yet other embodiments of the invention, substrate 25 may bemade very thick. The increased thickness of substrate 25 may provideenough stability such that a process flow like that shown in FIGS. 4(a)-(i) may be performed without the need for a carrier, such as carrier1. In addition, the increased thickness of substrate 25 may make it lessfragile. After a build of layers has been completed on the substrate 25,backgrinding or other machining processes (for example, lapping,milling, electrical discharge machining, chemical milling, fly cutting)of the substrate 25 may be performed to thin the substrate 25. Thinningof substrate 25 may be performed prior to dicing into individual die ifdesired.

Referring to FIG. 5( g), if substrate 25 is sufficiently conductive andof a suitable composition to allow for electrodeposition of materialused in making the desired multi-layer structure—either throughout itsbulk (as would be the case with solid metal) or by virtue of aconductive coating on surface 28 (e.g. a seed layer or seed layer andadhesion layer combination) and preferably one other surface (forexample, the bottom surface directly opposite top surface 28 (in whichcase the edges of substrate 25 may need to be coated to electricallyconnect surface 28 with the bottom surface)—then electrical contact withsurface 28 may be made through contacting means 11 (or even pressingmeans 9). As shown, contacting means 11 make contact with substrate 25on its bottom surface; however, contact through the side of substrate 25is another option, and contact with other surfaces is also possible. Inother cases, substrate 25 may be covered on top surface 28 by one ormore layers of material 31 (for example, sputtered or evaporated gold inthe range of 0.1-3.0 micrometers thickness on top of sputtered orevaporated titanium or chromium in the range of 0.01-0.1 micrometers inthickness).

In FIG. 5( g) it is assumed that conductive material 31 is required, andmaterial 31 has been deposited so as to cover surface 28 and extendacross material 23 and form an electrical connection to carrier 1.Carrier 1 is here presumed to be composed of a conductive material (forexample, electroless nickel-plated cast iron with low residual stress);if this is not the case, a conductive insert may be provided at the topof carrier 1 onto which material 31 can be deposited. By virtue ofeither contacting means 11 and conductive substrate 25, or else material31; surface 28 is now conductive and capable of receivingelectrodeposited material. In embodiments where conductive material 31is added, the substrate need not be conductive and contact means 11 neednot exist as electric connection is made directly by material 31 to thecarrier 1 and electrical connection between the carrier and an externalpower supply may be made in any appropriate way. In embodiments whereelectroplating solution is located only on the upper surface of material31, no shielding of other portions of the carrier fromelectrodepositions may be necessary but when no such limitation isplaced on the electroplating solution, it may be necessary to shield therest of the carrier in some manner.

In FIG. 5( h), a patternable mold material 33 has been applied tomaterial 31. The patternable mold material 33 is assumed to be a dryfilm photoresist. However, some embodiments of the invention may useother types of photoresist such as, but not limited to, liquid orelectrodepositable (electrophoretic) photoresists. In FIG. 5( h) thepatternable mold material 33 is shown being applied by a laminationroller 34. However, other embodiments of the invention may apply thepatternable mold material 33 by other means such as, but not limited to,vacuum laminating, roller coating, spraying, spin coating, ink-jetprinting, silk screening and the like.

According to some embodiments of the invention, different patternablemold materials (for example, photoresists) may be chosen for differentlayers based on their different properties. For example, somephotoresists may allow for thicker layers while others may allow for thepatterning of smaller features. Other photoresists may have betterchemical resistance to particular plating or etching baths. Thus, someembodiments of the invention may use a dry film photoresist on somelayers and a liquid or electrodeposited photoresist on other layers.Also, positive resist may be used on some layers, while negative resistmay be used on other layers. A single layer may also use more than asingle type of resist for patterning of a deposit.

The choice of photoresists may be based on such additional factors aswall geometries, different minimum feature capabilities of thephotoresist, whether a small positive feature or a small negativefeature is desired (for example, a small aperture or else a narrow wallor small post). Thus, some embodiments of the invention may analyze ageometry of a device or structure on a layer by layer basis in order todetermine the type of features that are present on a particular layer.Based on the results of that determination, a particular photoresist maybe chosen to pattern that layer. The geometry analysis may be performed,for example, by a suitable processing device running a suitable softwareprogram, or may be performed by hardware, firmware or a combinationthereof. For example, 3-D CAD software may be used to analyze thegeometry of a device by cross-sections. Based on this analysis, one typeof photoresist may be used for a cross-section having one thickness,while another photoresist might be used for a different cross-sectionhaving a different thickness. Similarly, the software might analyzefeature sizes on different layers of the device and differentphotoresists may be chosen for different layers based on the analysis.

Some embodiments of the invention may also modify patternable moldmaterial (e.g. dry film or liquid photoresist) development parameters ona layer-by-layer basis based on, for example, the wall geometries,different minimum feature capabilities of the photoresist, whether asmall positive feature or a small negative feature is desired. Exemplarymodifiable development parameters include, for example, developer andrinse droplet size, the pressures under which the developer and rinseare applied, and the like.

In addition, after a patternable mold material development and/orstripping process, residue of the patternable mold material may be morelikely to remain where particular geometries or feature sizes arepresent. Thus, some embodiments of the invention may determine on alayer by layer basis, for example, using software, whether there islikely to be a residue of patternable mold material remaining afterdevelopment and/or stripping of the patternable mold material based onparticular geometries or feature sizes. In this manner, removal ofresidue, or focused removal operations, may be performed only on thoselayers or portions of a layer where it is required. The residue ofpatternable mold material may be removed, for example, by a plasma etch.

As discussed above, one method for applying a photoresist is to use adry film laminator incorporating lamination roller 34 and secondaryroller 38 shown in FIG. 5( h). A schematic diagram of a laminator usedaccording to some embodiments of the invention, is shown in FIG. 8. Asshown, a roll of dry film resist 98 is located around one roller 34which is spaced from a second roller 38. As shown, the upper roller 34(adjacent to resist 98) would normally be heated. Substrate 106 (e.g. acircular disk) is pushed between the two rollers to apply the dry filmresist. Because of a non-uniform feeding effect that may occur due tothe non-rectangular shape of substrate 106 as it enters between the tworollers, the resist applied to the substrate 106 may be wrinkled orotherwise distorted.

Thus, some embodiments of the invention provide a carrying template forholding the substrate 106 (or substrate 106 in a carrier such as carrier1) as it is passed through the hot roll laminator 104. An exemplaryembodiment of a template 109 for this purpose is shown in FIG. 9( a).Template 109 comprises a plate including an aperture 110 passingentirely through the plate for holding the substrate 106. Aperture 110may be of a suitable size to properly receive and hold substrate 106. Insome embodiments, the template thickness is sized such that the topsurface of substrate 106 will be substantially flush with the topsurface of the template 109 (i.e., either flush with the top surface orwithin a small amount of being flush, for example, within onemillimeter). While secured in device 109, the lamination applied to thesubstrate 106 will be substantially undistorted as it enters between therollers because the rectangular front edge of the template 109 will begrabbed by the rollers rather than the wafer itself.

FIG. 9( b) shows another embodiment of a carrying template 112 that maybe used to hold substrate 106 during the lamination process. Carryingtemplate 112 differs from carrying template 109 shown in FIG. 9( a) inthat aperture 115 does not pass entirely through carrying template 112,but instead has a bottom as shown. The depth of aperture 115 may bechosen such that the top surface of substrate 106 will be substantiallyflush with the top surface of the template 109.

According to embodiments wherein multiple layers are added to thesubstrate during a process flow like that shown in FIGS. 4( a)-(i), itmay be required to use multiple templates for the lamination process.Each template may have a different thickness or aperture depthcorresponding to a new height of the substrate after an additional layeror layers has been added. According to other embodiments, the templatemay include shims or other height adjustment members that are used forthe initial layers. The shims may be removed or interchanged as theheight of the substrate increases. According to embodiments wherein thetop surface of substrate 106 is lower by a small amount than the topsurface of the template 109 (for example, by one millimeter) templatethickness or aperture depth may not require adjustment each time a newlayer is added (i.e., a given thickness or depth may cover a range ofsubstrate thicknesses).

An exemplary embodiment using shims is shown in FIGS. 10( a)-(b). InFIG. 10( a), template 112 holds substrate 106 before the addition of anylayers to the substrate. The substrate 106 sits on a suitable number ofshims 113 such that the top surface of the substrate is substantiallyflush with the top surface of the template 112. FIG. 10( b) showssubstrate 106 after a build 114 of layers has been added to thesubstrate. Shims 113 have been removed since the new height of thesubstrate allows the top surface of the substrate to be substantiallyflush with the top surface of the template 112 without the shims.

According to further embodiments, a screw adjustment, spring loader, orother suitable mechanism may be used in place of the shims in order tokeep the substrate 106 (or the top surface of build 114) substantiallyflush with the top of the template 112 or in another suitable position,for example, some distance above the top surface of the template 112.

According to yet other embodiments of the invention, the substrate mayitself have a rectangular shape. In this case, a template such astemplate 112 may not be required to avoid wrinkling or other distortionof the resist applied to the substrate.

When multiple layers are added to the substrate during a process flowlike that shown in FIGS. 4( a)-(i), as additional layers are added to asubstrate and laminated, the conditions of the lamination process may bealtered. As an example, as additional metal layers are added to thesubstrate, a point may be reached where the mass built on the substratebegins to pull excessive heat away from the resist (by means ofconduction and the increase in thermal mass) and thereby results in pooradhesion of the resist to the substrate or other problems.

Therefore, according to some embodiments of the invention, theconditions of lamination (for example, feed rate, roller temperature,pressure, and the like) may be altered during the process of formingmulti-layer structures (e.g. based on a determination of the thermalmass and conductivity of build 114 or more simply based on the totallayer height added). One embodiment of the invention provides a methodfor operating a lamination system wherein the identity of a substrateabout to enter the system is determined (for example, using the carrieridentification device 19 discussed above). Then, a determination ofthermal mass and conductivity is determined for the identified substratebased on, for example, determining the number of layers on thesubstrate, the total thickness of the layers, percentages and types ofmetals in the layers, and the like. Alternatively, in some embodiments,it may be sufficient to determine simply the total current layer heightand to adjust process parameters accordingly.

The lamination parameters are then adjusted to achieve optimal adhesionof the patternable mold material to the layer being laminated based onthe determined thermal mass and conductivity. According to someembodiments of the invention, the determination of thermal mass andconductivity and adjustment based thereon may be performed manually orautomatically, for example, by a suitable processing device running asuitable software program, or may be performed by hardware, firmware ora combination thereof.

To enhance adhesion of photoresist to material 31 or to any of thematerials that may be present on a previous layer of a multilayerstructure built according to some embodiments of the invention,microetches may be used. For example, microetchants suitable forenhancing adhesion to copper include CE-100 Copper Etchant (TranseneCompany Inc., Danvers, Mass.). Microetchants suitable for enhancingadhesion to nickel include TFB Nickel Etchant, Type 1 Nickel Etchant andTFG Nickel Etchant (Transene Company Inc., Danvers, Mass.).Microetchants suitable for enhancing adhesion to gold include GE-8148Gold Etchant (Transene Company Inc., Danvers, Mass.). Alternatively,mechanical roughening (e.g., application of abrasive such as pumice) maybe used to enhance adhesion. Alternatively, an adhesion promoter (e.g.,HMDS (hexamethyldisilazane) may be applied to the surface to be coatedwith resist, in which case special treatments (e.g., plasma etching) toremove traces of adhesion promoter after developing or stripping andbefore deposition of structural or sacrificial material may be required.

In some embodiments, structures will be formed using nickel or a nickelalloy as a structural material and using copper as a sacrificialmaterial. It is known that some dry film photoresists adhere better tocopper than nickel. As adhesion is important to successful layerpatterning, in some embodiments it may be desirable to enhance adhesionbetween a dry film, or other photoresist, and the substrate orpreviously formed layer. Such adhesion enhancement may occur in avariety of ways, for example (1) by roughening the surface of thesubstrate or previous layer to enhance mechanical bonding between thedry film, or other photoresist, and the surface, and/or (2) by applyinga material to the substrate that adheres well to the materials of theprevious layer and which can also chemically bond with the photoresist.For example, if the previous layer comprises regions of a first material(e.g. copper) and a second material (e.g. nickel), a dry film maychemically bond with first material upon pressing and/or heating whereasit may only mechanically bond with the second material. If a thin seedlayer of the first material or of another material that has similaradhesion properties may be applied to at least the regions of theprevious layer occupied by the second material, then good adhesionbetween the photoresist and the entire previous layer or substrate maybe achieved.

Depending on how the seed layer is applied; depending on whether it isacceptable for the seed layer material to exist between layers of thestructural material, between layers of the sacrificial material, and/orbetween layers of different materials; depending on the order ofdepositing the structural material and the sacrificial material; and/ordepending on the order of deposition of the first material and thesecond material different process flows may be defined which allow forsuccessful fabrication where good adhesion between photoresist andsubstrates and/or previously formed layers may be obtained.

For example, one such embodiment may contain the following steps oroperations: (0) assume the sacrificial material is the first materialand is the material that is to be deposited first; (1) apply a thin seedlayer (e.g. less than 1 micron, more preferably less than 0.5 microns,and even more preferably less than 0.2 microns) of sacrificial materialto the previously formed layer; (2) apply and pattern the photoresist,(3) deposit the sacrificial material to a height at least as great asthe layer thickness, which may for example be 2 microns or less, 5microns or less, 10 microns or less, and even 50 microns or more, (4)remove the photoresist, (5) perform a flash etch to remove a thicknessof sacrificial material equal to or somewhat greater than the height ofthe seed layer to exposure regions of structural material that exist onthe previous layer, and (6) selectively or blanket deposit thestructural material to a height at least as great as the layerthickness, and (7) planarize the deposited material to completeformation of the layer.

Another such embodiment might involve the following steps or operations:(0) assume the structural material is the second material and is thematerial that is to be deposited first; (1) apply a thin seed layer ofsacrificial material to the previously formed layer; (2) apply andpattern the photoresist, (3) perform a flash etch to remove exposedregions of the seed layer, (4) deposit the structural material to aheight of at least one layer thickness, (5) remove the photoresist, and(6) selectively or blanket deposit the sacrificial material to a heightat least as great as the layer thickness, and (7) planarize thedeposited material to complete formation of the layer. Other alternativeembodiments based on other build option selections are possible and willbe apparent to those of skill in the art upon reviewing the teachingherein.

In some alternative embodiments, steps or operations (5) and (4) (theseed layer removal operations) of the above two outlined embodiments,respectively, may be eliminated if the depositions are very thin tobegin with, or they may be partially eliminated by not necessarilytrying to eliminate all exposed seed layer material. It may not benecessary to completely remove all seed layer material if it is thinenough or made to be thin enough as extremely limited access to anysacrificial material located between successive regions of structuralmaterial on adjacent layers may substantially eliminate risk of etchingresulting in delamination. Such alternatives may also require that anysandwiched sacrificial material (i.e. located between layers ofstructural material) not have any other negative impact (e.g. reductionin strength of the structure, reduction in conductivity, or the like) onthe structure as it is intended to be used.

According to some embodiments of the invention, multiple layers ofphotoresist may be added in succession to the substrate to obtain athicker photoresist before any patterning of the photoresist isperformed. FIGS. 11( a)-(e) shows an embodiment of this process. In FIG.11( a), a substrate 115 is provided. In FIG. 11( b), a first layer ofphotoresist is applied, for example by the lamination roller 104 shownin FIG. 8( a). This process is repeated and a second layer ofphotoresist is applied, as shown in FIG. 11( c). This process isrepeated again and a third layer of photoresist is applied, as shown inFIG. 11( d). After a final layer has been applied, patterning of thethick photoresist may be performed, as shown in FIG. 11( e). In somealternative embodiments, exposure (i.e. latent patterning) may occurafter all layers of photoresist have been accumulated or exposure mayoccur one or more times prior to accumulating all layers of photoresist.In either alternative, development of photoresist is preferably delayeduntil after all layers of photoresist are formed.

Dry film resists may be used as the patternable mold material, accordingto some embodiments of the invention. Dry film resists typically come inlayers having a thickness between 10 and 50 microns. A thinner resistmay allow for smaller feature sizes. Thus, according to some embodimentsof the invention, after a single layer of dry film resist is applied tothe substrate, for example by the lamination roller 104 shown in FIG. 8(a) but before patterning the resist, the layer is thinned to a desiredthickness. Thinning of the dry film resist layer may be done in anysuitable manner, for example by plasma etching. Alternatively oradditionally, a suitable dilute chemical stripper may be used to thinthe dry film resist layer.

Alternatively, rollers or plates may be used to thin the dry film resistlayer by the application of pressure. It may desirable to have theroller or plate heated. In addition, because of the aqueous nature ofthe dry film resist layer, moisture may make the film more flowable.Thus, it may also be desirable to wet the dry film resist layer if aroller or plate is used. Also, the dry film resist layer may be thinnedby cutting with a tool, for example a diamond fly cutter. Further, thedry film resist layer may be thinned by abrading, for example bysandblasting or by lapping.

If a dry film resist is used, the supplied top cover sheet (not shown)may be removed to improve resolution capability. Exposure to oxygen maythen however inhibit polymerization, in which case the sheet may beremoved just prior to exposure. Some embodiments of the invention mayreplace the sheet with a thinner oxygen barrier, or exposure may beconducted in an inert gas such as nitrogen.

In some embodiments that use dry film or liquid based resists,non-planarities in the surface of an applied film or cured liquid resistmay be removed by a planarization operation prior to any exposure of thephotoresist, if it is believed that the surface irregularities may leadto irregularities in exposure of the resist. If it is difficult toachieve a planar coating of resist as a result of depressions orprotrusions on a surface to which the resist is applied, it is possiblethat two or more applications of resist, (e.g. liquid resist) possiblywith one or more intermediate curing operations, will lead to moreuniform, or planar, resist surfaces.

Referring now to FIG. 5( i), according to some embodiments of theinvention, material 33 has been removed (for example, by trimming) ifnecessary so it does not cover up alignment target pattern 35 on insert5. Trimming may be done, for example, by a mechanical knife or othersuitable cutting tool. Alternatively, trimming may be done by applyingpressure to an area adjacent to the area to be trimmed (i.e. to the areaof targets) and then tearing the material 33 away. Pressure may beapplied, for example, by a plate or tool having a sharp or serratededge. In some embodiments, the plate may contact material 33 only inareas adjacent to the desired tear but not in other areas, to preventdamage. According to other embodiments, the material 33 to be trimmedmay be isolated from the remainder, for example, by an elastomeric seal,and chemically dissolved by stripping or developing the material 33 tobe trimmed.

According to other embodiments, trimming of material 33 may be avoidedin several ways. For example, in some embodiments the roll of material33 may be slit to a width such that it will not cover alignment targetpattern 35 when applied. Further, roller 34 may be sized such that itscontact area is only as wide as the area to be laminated. In this case,the roller does not apply heat and pressure to the area of the carrieror substrate that includes the alignment targets. According to otherembodiments, a release film may be used to cover the targets. Thematerial 33 would then stick to the release film rather than toalignment target pattern 35. The release film may be, for example,mylar, and may be peeled away after lamination of the material.

In other embodiments, it may not be required to trim material 33 ifvacuum applied between substrate and photomask is used to temporarilydraw the material 33 up against the photomask surface to verifyalignment. In this case, material 33 may become flat against the maskand may not substantially distort or displace the image of the target.

Patterns 35 and 36 may be protected by coating inserts with a hardprotective layer. Cover 7 has been removed to expose patterns 35 and 36.Patterns 35 and 36 are each a diamond, cross, circle, square, or otherpattern suitable for precise optical alignment, preferably usingautomated machine vision equipment. According to some embodiments of theinvention, patterns 35 and 36 may be formed on inserts 5, the latterbeing rigidly mounted to carrier 1 (for example, as a press fit or witha suitable adhesive), or else may be formed directly on carrier 1 (forexample, by engraving or etching).

Referring to FIGS. 5( i)-(j), carrier 1 is affixed to stage 40 such thatphotomask 42—consisting of substrate 37 (for example, glass or quartz)and non-transmitting coating 39 that is patterned to form clear regions41 representing the cross-section of the first layer of the desiredstructure (or its complement)—is above patternable material 33.Photomask 42 is preferably arranged with coating 39 in close proximityto material 33. Photomask 42 may be coated with a non-adherent film suchas Teflon®, SYTOP® (Asahi Glass Co., Ltd.) or parylene to reduce therisk of material 33 adhering to it, especially if material 33 is dryfilm resist from which the cover sheet has been removed. To reducediffraction and improve resolution, some embodiments of the inventionprovide an index matching liquid (for example, water, not shown) in thegap between photomask 42 and material 33 to provide a refractive indexmore closely matching that of photomask substrate 37 and/or patternablematerial 33.

Referring to FIG. 5( j), according to some embodiments of the invention,the coating portion of mask 42 and the surface of material 31 areadjusted to be highly parallel. Since material 33 is relatively uniformin thickness, this can be accomplished by temporarily allowing pitch androll motion of carrier 1 on stage 40, raising carrier on stage 40 untilcoating 39 and material 33 are in contact, then preventing further pitchand roll motion and lowering carrier 1 again to produce a gap which willallow for relative alignment. Parallelism is required to obtain the bestresolution, to produce sidewalls that are substantially orthogonal tothe surface of substrate 25, and other distortions. According to someembodiments of the invention, various methods of aligned patterning maybe used, including, but not limited to, contact alignment, proximityalignment, stepper alignment, scanner alignment, or projectionalignment.

As shown in FIG. 5( j), photomask 42 is provided with alignment targetssuch as 43 and 45. For purposes of illustration, alignment target 43 isshown as necessarily having a clear field (i.e., free of coating 39except in a small area), while target 45 is shown optionally as having adark field (i.e., having coating 39 everywhere except in a smallregion); however, a clear field target is also suitable for target 45.Initially targets 43 and 35, and targets 45 and 36, respectively, arenot aligned, as shown in FIG. 5( j). Photomask and substrate targets aredesigned so that both remain visible when the photomask and target arewell-aligned.

FIG. 5( j) illustrates two alternative embodiments for imaging thealignment targets on both carrier 1 and photomask 42. The firstembodiment is illustrated by the imaging system 47 shown on the leftside of the figures. The second embodiment is illustrated by the twoimaging systems 51 and 53 shown on the right side of the figures.However, it should be understood that during the following discussion ofthe first and second embodiments, it is assumed that both the left andthe right side of the figures include the imaging systems of theembodiment under discussion.

Both embodiments allow for alignment of each successive photomaskpattern to carrier 1 (i.e., to substrate 25) rather than to thepreviously-deposited layer, to advantageously avoid the accumulation oferrors that can lead to poor registration of layers. In the firstapproach, imaging system 49 (here assumed to be an electronic camerawith microscope optics, though direct observation is also possible withthe second embodiment) can be moved vertically on precision stage 50,preferably having excellent straightness of travel with minimal roll,pitch, and yaw or translation other than axial. Stage 50 is preferablyaligned so that its axis of travel is both extremely parallel to theoptical axis of system 49, and extremely perpendicular to the photomaskbottom surface (i.e., coating 39).

In the position shown, system 49 can focus on target 35 in its currentposition. As layers are added and carrier 1 descends gradually, system49 can be lowered on stage 50 in order to remain focused on target 35even if the amount of motion of carrier 1 exceeds the depth of focus ofthe optics of system 49 (for example, several microns or tens ofmicrons). System 49 can also be raised (shown as phantom lines 47) tofocus on photomask target 43. It should be noted that the directionsindicated (raised, lowered, etc.) refer to the figures and that otherembodiments are possible in which the apparatus moves in otherdirections than those shown. It should also be noted that although inthe embodiment shown the photomask is stationary while the substratemoves, other embodiments may keep the substrate stationary, while thephotomask moves. In this case, the optics of system 49 looking atphotomask may move with the photomask.

According to the second embodiment, two imaging systems 51 and 53 areused to independently (and if desired, simultaneously) focus on targets45 and 36, respectively. Thus, there are two different focal points. Ifdesired, the optical axes of systems 51 and 53 can be made coaxial (notshown) through the use of, for example, a beamsplitter or similardevice. System 53 can be lowered on stage 52 (similar to stage 50 interms of precision and alignment, but optionally with shorter travel) inorder to remain focused on target 36. System 51 may remain fixed andfocused on target 45. Both embodiments are shown by way of illustration.However, normally one embodiment or the other may be used for alignmentof all targets that are used (the minimum number of targets needed toobtain alignment in X, Y, and theta (rotation) is two).

Assuming that the first embodiment is being used and that there are twotargets each on both photomask 42 and carrier 1, then in FIG. 5( j) thefocused images of targets 43 (now assumed to be two distinct targets)are formed by imaging systems 49 (now assumed to be two distinct imagingsystems) when raised into focus (as shown by phantom lines 47) usingstage 50. When systems 49 are at a lower position of stage 50, thefocused images of targets 35 are formed by them.

Images are recorded of targets 43 and 35 and compared (for example, bysuperimposing them) by an operator or by a machine vision system todetermine the degree of misalignment, and carrier 1 is repositioned inX, Y, and theta to achieve alignment, as is shown in FIG. 5( k). Notethat target 43 must be designed so as to allow target 35 to be viewedthrough it.

Assuming that the second embodiment is being used and that there are twotargets each on both photomask 42 and carrier 1, then in FIG. 5( j) thefocused images of targets 45 (now assumed to be two distinct targets)are formed by imaging systems 51 (now assumed to be two distinctsystems). When imaging systems 53 (now assumed to be two distinctsystems, for a total of four imaging systems, i.e. two on the left andtwo on the right of the FIGS.) are at a lower position of stage 52, thefocused images of targets 36 (now assumed to be two distinct targets)are formed by them.

Images are recorded of targets 45 and 36 and compared (for example, bysuperimposing them, which can be done electronically even though thetargets are not physically overlapping) by an operator or by a machinevision system to determine the degree of misalignment, and carrier 1 isrepositioned in X, Y, and theta to achieve alignment, as is shown inFIG. 5( k). Note that photomask 42 requires a clear region 54 throughwhich to view target 36, but target 45, which is not coincident withregion 54, can have any suitable geometry and be either clear or darkfield.

According to some embodiments of the invention, as layers are added tosubstrate 25, the focus of the imaging systems may be adjustedautomatically by lowering the imaging system by an amount that is basedon data regarding the thickness of the layer that has been added. Inaddition, the data regarding the thickness of the layer may be used toverify that an expected thickness of a layer that has been addedactually has that thickness. For example, when the imaging system islowered a specified amount based on the thickness data, the imagingsystem should be focused properly. If the imaging system is not focusedproperly, this may indicate that the layer does not have the expectedthickness. Such a determination may require that a patternable moldmaterial layer thickness is consistent. The automatic adjustment anddetermination may be performed, for example, by a suitable processingdevice running a suitable software program, or may be performed byhardware, firmware or a combination thereof.

According to other embodiments, an imaging system including a camerausing a large depth of focus, such as a long-working distance lens or atelecentric lens may be used in place of the cameras discussed above. Inthis case, movement of the imaging system may be avoided, as the largedepth of focus of the lens may be sufficient to cover a large gapbetween targets 43 or 45 and targets 35 or 36.

According to another embodiment of the invention, backside alignment maybe performed by placing targets on the back side of carrier 1. Referringto FIGS. 28( a)-(b), photomask 144 is provided with alignment targets145 and 146. Carrier 1 is provided with alignment targets 147 and 148,which are formed on the backside of the carrier 1 (for example, as apress fit), or else may be formed directly on carrier 1 (for example, byengraving or etching). As shown in FIG. 28( a), back-side imaging system149 includes two cameras which face upward towards the photomask 144.

Initially, imaging system 149 stores the images of alignment targets 145and 146 on photomask 144. Then, as shown in FIG. 28( b), carrier 1 isplaced between imaging system 149 and photomask 144. The live images ofthe alignment targets 147 and 148 are aligned with the previously storedimages of alignment targets 145 and 146.

Backside target alignment as described above is advantageous for variousreasons. For example, because the targets 147 and 148 are isolated fromthe patternable mold material being applied, they cannot be obscured bythe patternable mold material. Also, the targets 147 and 148 cannot bedamaged by lapping or other abrading operations performed on theopposite side of carrier 1 or by plating baths to which the targets maybe exposed. In addition, when using back side alignment, as more layersare added to carrier 1, there is no limitation to the number of layersthat may be added to the substrate because the photomask will not comein contact with the imaging system, as it might in the front sidealignment system previously described.

The embodiments described above for performing alignment in relation toalignment targets located on the carrier are equally applicable toembodiments of the invention having alignment targets located on thesubstrate, as will be discussed below.

Whatever embodiment is used for alignment, once photomask 42 and carrier1 are in alignment, carrier 1 is preferably raised on stage 40 so thatcoating 39 is in contact with material 33, as shown in FIG. 5( k), priorto exposing material 33. Vacuum may be applied between photomask 42 andcarrier 1 to increase contact pressure, and carrier 1 may be providedwith specialized means of obtaining a vacuum seal against photomask 42,such as an elastomeric seal. Alternatively, a seal entirely made fromelastomer or at least whose upper surface is elastomeric may be providedon stage 40, surrounding carrier 1. Similarly, contact between coating39 and the surface of material 33 can be improved by applying gaspressure to force the two together.

In FIG. 5( l), material 33 is being exposed to light (for example,ultraviolet) that is preferably highly-collimated and which passesthrough photomask 42 in clear regions 41. In FIG. 5( m), photomask 42has been removed and material 33 has been developed to yield a patterncorresponding to that of coating 39, with regions 57 no longer coveringmaterial 31. Note that in the example illustrated, material 33 behavesas a negative-working resist, becoming insoluble to the developer inthose regions exposed to light. According to other embodiments, amaterial with the opposite (positive-working) characteristics may alsobe used.

Development, in the case of a dry film photoresist, may be performed by,for example, spraying an alkaline aqueous developer at coating 33 in acontrolled and uniform fashion and at the correct temperature, followedby rinsing. To develop dry film photoresist so as to achieve good yieldon small features and as uniform development as possible, aclosely-spaced array of direct-fan or atomizing nozzles (for example,air-atomizing nozzles behaving like an airbrush) with a narrow sprayangle (for example, 15 degrees) may be used for both developing andrinsing. These nozzles may be arranged in several closely-spacedstaggered rows if they cannot be closely enough spaced in a single row.Some overlap between the nozzles may be provided to improve uniformity.If nozzles with a fan-type spray pattern are used, the major axis of thefan may be rotated by a small angle (for example, 15 degrees) from thenormal to the direction of travel of the resist to minimize interferenceand turbulence of one nozzle with its neighbor. The use of a narrowspray angle and close spacing of nozzles provides an angle of incidenceof the developer or rinsing solution that is as uniformly orthogonal aspossible to the resist surface. This is in contrast to developing andrinsing equipment commonly used in the fabrication of printed circuitboards, in which a few, widely-spaced nozzles with large spray angles(for example, 45 degrees or more) are common. Also, in contrast tonormal processing wherein resist is moved slowly and unidirectionallywith respect to the nozzles, some embodiments of the invention may moveresist bidirectionally and quickly with respect to the array of nozzlesso as to improve uniformity of processing and yield, minimizing theprocessing that occurs with pooled (vs. ejected) liquid. If all ofcoating 33 is not removed in regions 57 (for example, a thin residueremains), this may be removed by methods such as plasma etching (forexample, in an oxygen plasma), mechanical abrasion, and the like, suchthat material may be electrodeposited onto material 31 and excellentadhesion obtained.

In FIG. 5( n), optional insulating material 59 has been applied over theedge of material 31 to prevent electrodeposited material from beingdeposited near the edge of material 31. Preferably material 59 is easilyremovable (for example, by melting or chemical dissolution). In FIG. 5(o), substrate 25 has been immersed in an electrodeposition tank.Conventionally, the substrate itself may seal against theelectrodeposition tank. However, some embodiments of the invention, asshown in FIG. 5( o), allow carrier 1 to seal against tank 62. Gasket 61makes contact with material 31 or, as shown, with material 59, forming aseal which prevents deposition in the vicinity of insert 5 or on anyother portion of carrier 1. As shown, the carrier is located on thefloor of the electrodeposition tank; however, the carrier may also belocated in the ceiling or wall of the tank, or in a fixture that isplaced into the tank. According to some embodiments of the invention,the plating bath in the electrodeposition tank may include a fillermaterial along with a plating material. The filler material mayaccelerate the deposition rate of a plating material during the platingprocess. For example, when the plating material is copper, the fillermaterial may be copper particles. In addition to metal particles, hollowor solid polymer spheres, ceramic particles, and other materials whichdisplace volume and can be co-deposited with plating material so as toincrease deposition rate may be used. Such particles may also beincorporated into an anode used during the plating process.

According to some embodiments of the invention wherein an adheredpatterned material is used as the patternable mold material, in order toimprove uniformity of deposition rate counter electrode 64 may belocated at a closer proximity to the surface of the mold material in thebath 60 than is shown in FIG. 5( o), in some embodiments being incontact or near-contact with the mold material.

Tank 62 is filled with electrodeposition bath 60 and counter electrode64 is placed inside bath 60. Current is applied through bath 60 usingpower supply 66. As shown, supply 66 provides a direct current of aspecific polarity which may be continuous or pulsed. However, if thematerial to be deposited requires a cathode counter electrode thepolarity would be reversed. Also, some embodiments of the invention mayuse a supply of ‘pulse-reverse’ current in which the current changespolarity periodically. By the application of current from supply 66,deposit 63 of a first material is created in regions 57.

In FIG. 5( p), the remaining regions of material 33 are removed, leavinga patterned deposit of material 63 with blank regions 76. Such‘stripping’, in the case of a dry film photoresist, may be performed byspraying an appropriate alkaline aqueous ‘stripper’ at coating 33 in acontrolled and uniform fashion and at the correct temperature. If all ofcoating 33 is not removed by the stripper (for example, a thin residueremains in regions 76), this may be removed by methods such as plasmaetching (for example, in an oxygen plasma), mechanical abrasion, and thelike, such that material may be electrodeposited in regions 76 ofmaterial 31 and excellent adhesion obtained.

In FIG. 5( q), substrate 25 has been immersed in an electrodepositiontank. As shown, carrier 1 forms the floor of tank 68. Gasket 74 makescontact with material 31 or, as shown, with material 59, advantageouslyforming a seal which prevents deposition in the vicinity of insert 5 oron any other portion of carrier 1. Tank 68 is filled withelectrodeposition bath 72 and counter electrode 70 is placed inside bath72. Current is applied through bath 72 using power supply 78. As shown,supply 78 provides a direct current of a specific polarity which may becontinuous or pulsed. However, if the material to be deposited requiresa cathode counter electrode the polarity would be reversed. Also, asupply of ‘pulse-reverse’ current may also be used in which the currentchanges polarity periodically. By the application of current from supply78, deposit of a second material 65 is created in regions over material63, contacting material 31 in regions 76.

According to some embodiments of the invention, one of the first andsecond materials is a structural material, while the other is asacrificial material. The patternable mold material used (for example,photoresist or solder mask) may be one that is capable of achieving onlysmall positive features (for example, walls or posts). Alternatively,the patternable mold material may be one that is capable of achievingonly small negative features (for example, holes or slots). Someembodiments of the invention may select the order in which thesacrificial and structural materials are deposited for a particularlayer having a particular patternable mold material deposited thereon,based on characteristics of features that are to be patterned on thelayer and whether the particular patternable mold material producessmaller positive or negative features with better yield or quality (ifboth are not produced equally). For example, the order of deposition maybe selected based on whether small negative or small positive featuresof structural material are to be patterned on the layer. Referring toFIG. 12( a), as an example of a small positive feature, a small narrowwall of metal (for example nickel) is shown after patterning. Referringto FIG. 12( b), as an example of a small negative feature, a smallnarrow aperture surrounded by a metal (for example nickel) is shownafter patterning.

Furthermore, the order of deposition may be selected based on an aspectratio of a feature or features. As an example, as shown in FIG. 13,sacrificial material 118 is deposited on substrate 108 in a pattern.Structural material 119 is blanket deposited over sacrificial material118 and into the aperture as shown. If the aspect ratio of the apertureis too high, there may be a void, i.e., structural material 119 may notpenetrate to the bottom of the aperture due to deposition on thesidewalls of material 118 competing with deposition onto substrate 108.In such a case, it would be desirable to first deposit the structuralmaterial 119 rather than the sacrificial material 118, since the firstdeposition would be within an insulating material (for example,photoresist or solder mask).

As another example, the order of deposition may be determined on a layerby layer basis based on a desired grain structure for a structuralmaterial. The grain structure of the structural material may vary basedon whether the structural material is deposited before or after thesacrificial material is deposited. If the structural material isdeposited into an aperture wherein the walls of the aperture arepatternable mold material and thus non-conductive, a particular grainstructure will occur wherein the grains grow from the bottom of theaperture in an upward direction. However, if the structural material isdeposited into an aperture wherein the walls of the aperture are aconductive material that was deposited first (for example, thesacrificial material), a different grain structure will occur whereinthe grains grow laterally from the walls of the aperture as well as fromthe bottom of the aperture in an upward direction. Either grainstructure may be desirable for particular applications.

As an example of a process for patterning a small positive feature ofstructural material—the small narrow wall shown in FIG. 12( a)—using apatternable mold material that produces better or higher-yieldingpositive features, some embodiments of the invention may, for aparticular patternable mold material, deposit a sacrificial materialfirst and then deposit a structural material, as illustrated in FIGS.14( a)-(h). FIGS. 14( a)-(h) show an embodiment of a process for formingthe narrow wall shown in FIG. 12( a). In FIG. 14( a), a substrate 108 isshown, onto which patternable mold material 117 (for example,photoresist or solder mask) has been deposited as shown in FIG. 14( b).In FIG. 14( c), material 117 has been patterned (for example, if aphotoresist, by use of a photomask, developing, etc., by laser directimaging, a pattern generator and the like or, a combination of thesemethods) to produce a small wall of material 117. In FIG. 14( d),sacrificial material 118 (for example, a metal such as copper) has beendeposited around the small wall of material 117 (for example, byelectrodeposition).

In FIG. 14( e), material 117 has been removed (for example, by use of achemical stripper) to expose regions of the substrate 108 which are notcovered with sacrificial material 118, leaving an aperture having thedesired pattern. In FIG. 14( f), structural material 119 (for example, ametal such as nickel) has been deposited over the entire substrate 108and into the aperture. In FIG. 14( g), the layer has been planarized toa sufficient depth to remove all of structural material 119 overlyingsacrificial material 118, and also to establish a layer of the desiredthickness, flatness, and surface finish. The sacrificial material 118 isthen ultimately removed, as shown in FIG. 14( h), leaving the desirednarrow wall of structural material 119.

As an example of a process for patterning a small negative feature ofstructural material (for example, the small narrow aperture shown inFIG. 12( b)) using a patternable mold material that produces better orhigher-yielding positive features, some embodiments of the inventionmay, for a particular patternable mold material, deposit a structuralmaterial first and then deposit a sacrificial material, as illustratedin FIGS. 15( a)-(e). FIGS. 15( a)-(e) show an embodiment of a processfor forming the narrow aperture shown in FIG. 12( b). In FIG. 15( a), asubstrate 108 is shown, onto which patternable mold material 117 (forexample, photoresist or solder mask) has been deposited as shown in FIG.15( b).

In FIG. 15( c), material 117 has been patterned (for example, if aphotoresist, by use of a photomask, developing, etc., by laser directimaging, a pattern generator and the like or, a combination of thesemethods) to produce a small wall of material 117. In FIG. 15( d),structural material 119 (for example, a metal such as nickel) has beendeposited around the small wall of material 117 (for example, byelectrodeposition). The photoresist is then removed, as shown in FIG.15( e), leaving an aperture in the nickel. Sacrificial material (forexample, a metal such as copper) (not shown) may then be blanketdeposited (for example, by electrodeposition) over the substrate to formother structures if necessary.

The determination of whether the structural or sacrificial material isdeposited first may be performed, for example, by a suitable algorithmthat analyzes cross sections of each layer and makes the determination.The determination may be made based on various factors. For example,some embodiments of the algorithm may determine whether a predefinedminimum feature size for positive or negative features exists (forexample, 10 or 20 microns) on a layer being analyzed. Other embodimentsof the algorithm may determine whether a predefined number of positiveor negative features on a layer have a predetermined minimum featuresize (for example, 10 or 20 microns). Yet other embodiments of thealgorithm may assess the importance of having accurate features on aparticular layer. Further embodiments of the algorithm may determine theaspect ratios of features on an analyzed layer. The algorithm may beperformed by software, hardware, firmware or a combination thereof.

A flowchart of an exemplary embodiment of an algorithm for determiningpriority of deposition is shown in FIG. 16, assuming in this case thaton the layer being considered one is using a patternable mold materialthat produces better or higher-yielding positive features. At S1601, thelayer of interest is analyzed. At S1602, it is determined whether thelayer has a feature with the predefined minimum feature size. If thereis not such a feature, then no determination of priority of depositionof the sacrificial and structural materials is made (S1603). If there issuch a feature, then at S1604 it is determined whether the feature is apositive feature or a negative feature in the structural material forthat layer. If the feature is negative, then at S1605 the structuralmaterial is deposited first. If the feature is positive, then at S1606the sacrificial material is deposited first.

The dimensions of the actual negative and positive features (for examplethose shown in FIGS. 12( a)-(b)) may not be the same as the nominal,i.e., specified dimensions, selected using, for example, computer aideddesign software. As an example, the nominal width of a positive featuremay be designed to be 20 microns, but the actual feature may have awidth of 18 microns, while an actual negative feature may have an widthof 22 microns, or vice versa. The deviation or offset of the actualdimension from the nominal dimension may not be symmetric in relation tothe nominal dimension. In other words, an actual negative feature havinga nominal width of 20 microns may have an actual width of 23 microns,while an actual positive feature having a nominal width of 20 micronsmay have an actual width of 18 microns.

Some embodiments of the invention may determine in advance what thedimension offset will be and may pre-scale edges of a feature, forexample using computer aided design software, in order to compensate forany anticipated offsets. Photomasks may thus be created wherein thepatterns for patterning positive and negative features includeasymmetrical offsets.

Referring now to FIG. 5( r), according to some embodiments of theinvention, carrier 1 is placed in planarization fixture 67. Fixture 67consists of ring 80 with hard stops 82, sliding stages 69, and support71. Stops 82 are co-planar and formed from a material (for example,polycrystalline diamond, silicon carbide, cubic boron nitride, oraluminum oxide) that wears slowly on plate 73. As shown, surface 3 ofcarrier 1 mates with support 71. The mating surface of support 71 isadjusted to be extremely parallel with the bottom surface of stops 82,such that as stages 69 descends, materials 63 and 65 will becomeplanarized such that their surface will be very parallel to surface 3.Stages 69 are distributed on the inside of fixture 67 preferably atuniform intervals (e.g., 3 stages 120 degrees apart, 4 stages 90 degreesapart). Alternatively, it is possible to make the surface of carrier 1that is opposite surface 3 (i.e., the backside of the carrier) highlyparallel to surface 3, and provide in fixture 67 a support analogous tosupport 71 which mates with the backside of carrier 1. Stages 69 mayalso be replaced by a single stage or linear bearing above carrier 1 andmounted to its backside.

The mating surface of support 71 or its analog may be aligned to beparallel with the bottom of stops 82 by various methods, including theuse of an autocollimator. This alignment may also be performed oncecarrier 1 is held in fixture 67, a more direct and probably morereliable method for achieving the desired parallelism between surface 3and the bottom of stops 82. In this case, a region of a surface ofcarrier 1 (for example, the rear surface opposite surface 3) may begiven optical smoothness and flatness, as well as a high degree ofparallelism to surface 3, to allow alignment using an autocollimatorcalibrated to establish perpendicularity to the plane of stops 82.

With carrier 1 in fixture 67, materials 63 and 65 are planarized by theuse of an abrasive (for example, diamond, aluminum oxide) applied toplate 73, which may be, for example, a lapping plate made of materialssuch as copper, tin-antimony, cast iron, and copper-resin composite.Alternatively, plate 73 may be composed of an abrasive material andplanarization performed by the application of an appropriate lubricant.The planarization process is stopped before materials 63 and 65 arereduced to their final desired thickness.

As shown in FIG. 5( s), according to some embodiments of the invention,measurement sensors 75 are used to measure the thickness of materials 63and 65 (hereinafter called ‘the layer’). Such sensors may be, forexample, dial indicators with high resolutions, LVDT (linear variabledifferential transformer)-based distance gauges, and the like.Alternatively, non-contact sensors based on light, eddy currents,capacitance, and so forth may be used. Measurements of layer thicknessare made by comparing the readings of sensors 75 which measure theposition of surface 3 with that of sensors 84 which measure the positionof the current as-planarized surface, with both sensors preferablyconnected to a common support.

Alternatively, if mechanical contact is used, either sensors 75 or 84(but not both) may be replaced by a fixed-length ball or other probe tipwhich is mechanically connected to the sensor, reducing the total lengthof material between sensor and ball so as to minimize variation due totemperature fluctuations and mechanical deflection. Additional sensorssimilar to sensors 75 and 84 may be provided to determine uniformity ofplanarization (for example, to determine whether the surface is flat ismay be desirable to place multiple sensors at various radii from thecenter of substrate 25).

After sensing of layer thickness is performed, if additionalplanarization is required to achieve the desired thickness or flatnessof the layer, it is performed as shown in FIG. 5( r), and additionalsensing may be done to verify the result as shown in FIG. 5( s),possibly in an iterative fashion. In FIG. 5( t), a layer having a finaldesired thickness and flatness has been produced, with surface 77serving as substrate for subsequent layer depositions. After the layeris planarized, a small region 79 of material 65 may remain on theperiphery of the deposited area. This completes the formation of asingle layer of a multi-layer structure, according to some embodimentsof the invention.

Formation of a second layer, according to some embodiments of theinvention, begins with a process of patterning a mold material,analogous to that already described in FIGS. 5( h)-(m), but typicallyusing a different photomask pattern representing the secondcross-section of the multi-layer structure, which in general isdifferent from that used to pattern the first layer. Different moldmaterial may also be used.

In FIG. 5( u), a patternable mold material 83 (here assumed to be aliquid photoresist, but it may be, for example, a dry film photoresistor an electrodeposited photoresist as well) has been applied to layersurface 77. In some embodiments the resist is applied on top of anantireflection coating 81 to avoid distortions that may be encounteredwhen an area where a feature is to be patterned overlies two or morematerials on a previous layer. The problem results from the fact thatthe two or more underlying materials may each have a differentreflectivity and/or may each have a different surface finish. As aresult, the patternable mold material overlying the materials in whichthe feature is patterned may have varying amounts of exposure due to thevarying reflection of light from the underlying materials. This mayresult in a distorted feature. The use of the antireflection coating 81may reduce such distortion by allowing for a more uniform exposure ofthe patternable mold material.

If a liquid or electrodeposited photoresist is used, a baking step maybe required to dry the liquid photoresist or to consolidate particles inthe case of an electrodeposited photoresist. If a carrier is used or ifthe substrate is thick, a hot plate may be insufficient to perform thisbaking step. Thus, some embodiments of the invention bake thephotoresist using, for example, an oven or infrared or microwaveradiation. Whether a hot plate, oven or radiation method is used to bakethe photoresist, it may be cooled by placing it on a cool plate, in arefrigerated chamber, or in a flowing stream of air. Such methods mayalso be used to cool dry film photoresist and laminated substrates afterlamination.

Material 83 may be applied by spinning carrier 1 (as assumed here) or byother methods, resulting in an excess thickness 86 (i.e., an edge bead).In FIG. 5( v) excess material thickness 86 has been removed, forexample, by chemical dissolution, typically along with some underlyingmaterial 83 and material 83 is soft-baked if necessary or otherwiseprocessed to prepare it for exposure. Cover 7 has also been removed toexpose patterns 35 and 36.

In FIG. 5( w), carrier is affixed to stage 40 such that photomask 85(consisting of substrate 86 and non-transmitting coating 87) is abovematerial 83. Photomask 85 is preferably arranged with coating 87 inclose proximity to material 83. Photomask 85 may be coated with anon-adherent film to avoid material 83 from adhering to it. To reducediffraction and improve resolution, a liquid may be provided in the gapbetween photomask 85 and material 83 to more closely match refractiveindex. Coating 87 and the surface of material 31 are adjusted to behighly parallel, as before.

In FIG. 5( x), photomask 85 and carrier 1 have been brought intoalignment as before with photomask 42 and carrier 1. Carrier 1 is alsoraised on stage 40 so that coating 87 is in contact with material 83prior to exposing material 83.

In FIG. 5( y), material 83 is being exposed to light (for example,ultraviolet) that is preferably highly-collimated and which passesthrough photomask 85 as before. In FIG. 5( z), photomask 85 has beenremoved and material 83 has been developed to yield a patterncorresponding to that of coating 87 as before. Note that in the exampleillustrated, material 83 behaves as a negative-working resist, becominginsoluble to the developer in those regions exposed to light; a materialwith the opposite (positive-working) characteristics may also be used.

If all of material 83 is not removed in regions 90 (for example, a thinresidue remains), this may be removed by methods such as plasma etching(for example, in an oxygen plasma), mechanical abrasion, etc. such thatmaterial 89 may be electrodeposited onto the previous layer (comprisingmaterials 63 and 65) and excellent adhesion obtained, as shown in FIG.5( aa). After complete removal of material 83 as before, material 91 isdeposited in its place, as before. In FIG. 5( aa), planarization ofmaterial 89 and 91 has been performed, and a third layer, comprisingmaterials 92 and 94 has been fabricated as before.

FIGS. 17( a)-(h) illustrate a method for achieving both small positiveand negative features in the same layer when the patternable moldmaterial (for example, photoresist or solder mask) cannot produce smallfeatures of both types equally well at least according to someembodiments of the invention. In the example illustrated, it is assumedthat positive features in the mold material are more easily produced. InFIG. 17( a), patternable mold material 117 is patterned (for example, ifa photoresist, by use of a photomask, developing, etc., by laser directimaging, a pattern generator and the like or, a combination of thesemethods) and first material 120 (for example, copper) is deposited (forexample, by electrodeposition). In FIG. 17( b), patternable moldmaterial 117 is removed. In FIG. 17( c), patternable mold material 117is deposited over first material 120. In FIG. 17( d), patternable moldmaterial 117 is patterned and it is assumed that the remaining region ofmold material 117 as shown in FIG. 17( d) is narrower than a negativefeature that could have been formed for example in obtaining the stateof the process shown in FIG. 17( a).

In FIG. 17( e), a second material 121 (for example, nickel) is deposited(for example, by electrodeposition). In FIG. 17( f), patternable moldmaterial 117 is removed. In FIG. 17( g), first material 120 is blanketdeposited over second material 121. In FIG. 17( h), the layer has beenplanarized to a sufficient depth to establish a layer of the desiredthickness, flatness, and surface finish. It will be understood by oneskilled in the art that a similar process for achieving both smallpositive and negative features in the same layer as that described abovein reference to FIGS. 17( a)-(h) may be performed when a patternablemold material that more easily produces small features that are negativeis used on a layer.

It may desirable to deposit more than two materials on a single layer.FIGS. 18( a)-(k) show a process for depositing more than two materialson a single layer, according to some embodiments of the invention. InFIG. 18( a), a substrate 108 is shown, onto which patternable moldmaterial 117 (for example, photoresist or solder mask) has beendeposited as shown in FIG. 18( b). In FIG. 18( c), material 117 has beenpatterned (for example, if a photoresist, by use of a photomask,developing, etc., by laser direct imaging, a pattern generator and thelike or, a combination of these methods) to produce apertures. In FIG.18( d), first material 122 (for example, a metal such as copper) hasbeen deposited into the apertures (for example, by electrodeposition).

In FIG. 18( e), material 117 has been removed (for example, by use of achemical stripper) to expose regions of the substrate 108 which are notcovered with first material 122. In FIG. 18( f), material 117 (or analternative patternable mold material) is deposited over first material122 and patterned (FIG. 18( g)). In FIG. 18( h), second material 123(for example, a metal such as nickel) has been deposited. In FIG. 18(i), material 117 is removed. In FIG. 18( j), a third material 124 (forexample, silver) has been blanket deposited over materials 122 and 123.In FIG. 18( k), the layer has been planarized to a sufficient depth toremove all of second material 124 overlying first material 122 andsecond material 123, and also to establish a layer of the desiredthickness, flatness, and surface finish.

Various alternatives to the embodiment of FIGS. 18( a)-18(k) arepossible. For example, in some alternative embodiments, it may possibleto planarize materials 122 and 117 of FIG. 18( d) to a desired height(e.g. equal to or greater than the layer thickness or bounding height ofthe layer) prior to removal of material 117 as shown in FIG. 18( e). Inaddition, or alternatively, it may be possible to planarize material 117deposited in FIG. 18( f) prior to patterning it to obtain the void inmaterial 117 as shown in FIG. 18( g). The planarization may or may notcause material 122 to become exposed but it is anticipated that theplanar surface of material 122 may allow more accurate patterning ofmaterial 117 in obtaining the result of FIG. 18( g) particularly if thevoid or voids to be formed in material 117 are near or adjacent to thedeposits of material 122. Such planarization may allow the materials tobe pattern deposited adjacent to or in proximity to one another. It isbelieved that these alternatives will work satisfactorily when thepatternable material, for example is a photoresist of the dry film orliquid type, so long as it is adequately located within corners betweenmaterial 122 and the substrate or previously formed layer of material.In still other alternative embodiments, it may be possible to furtherpattern the first deposited patternable masking material instead ofremoving it which was shown FIG. 18( e) such that depositing a secondpatternable material as shown in FIG. 18( f) becomes unnecessary.

Additional embodiments where three or more materials per layer will bedeposited are possible. Some of these additional embodiments are focusedon alternative techniques for allowing patterned deposition of two ormore materials adjacent to one another. Detailed examples of suchalternative embodiments are set forth herein next as the first throughthird exemplary embodiments.

Referring to FIGS. 19( a)-(k), a first exemplary embodiment is shown fordepositing more than two materials on the same layer wherein two or moredifferent materials (for example, metals) need to be pattern depositedadjacent to each other. In FIG. 19( a), a substrate 108 is shown, ontowhich patternable mold material 117 (for example, photoresist or soldermask) has been deposited as shown in FIG. 19( b). In FIG. 19( c),material 117 has been patterned (for example, if a photoresist, by useof a photomask, developing, etc., by laser direct imaging, a patterngenerator and the like or, a combination of these methods) to produce anaperture. In FIG. 19( d), first material 122 (for example, a metal suchas copper) has been deposited into the aperture (for example, byelectrodeposition).

In FIG. 19( e), material 117 has been removed exposing portions of thesubstrate 108 not covered by first material 122. In FIG. 19( f), anotherlayer of material 117 is deposited over substrate 108 and first material122. In FIG. 19( g), material 117 (or an alternative patternable moldmaterial) is patterned to produce an aperture adjacent to first material122, as well as to expose a top portion of first material 122. In FIG.19( g), it is shown that an edge of the material 117 that is formed overfirst material 122 is not aligned with an edge of first material 122,i.e., a portion of the top surface of first material 122 is exposed. InFIG. 19( h), second material 123 (for example, nickel) is deposited intothe aperture and over the exposed portion of first material 122. In FIG.19( i), material 117 is removed. In FIG. 19( j), third material 124 (forexample, silver) is blanket deposited over substrate 108, first material122 and second material 123. In FIG. 19( k), the layer has beenplanarized to a sufficient depth to establish a layer of the desiredthickness, flatness, and surface finish. It can be seen in FIG. 19( k)that the portion of second material 123 that was deposited over firstmaterial 122 has been removed. Thus, it was not necessary that the edgeof the material 117 that is formed over first material 122 be alignedwith an edge of first material 122. Therefore, some embodiments of theinvention purposely do not align the edge, as shown in FIG. 19( g). Thismay be beneficial in that precise mask alignment is not necessary.

Referring to FIGS. 20( a)-(j), a second exemplary embodiment is shownfor depositing more than two materials on the same layer wherein two ormore different materials (for example, metals) are adjacent to eachother. In FIG. 20( a), a substrate 108 is shown, onto which patternablemold material 117 (for example, photoresist or solder mask) has beendeposited as shown in FIG. 20( b). In FIG. 20( c), material 117 has beenpatterned (for example, if a photoresist, by use of a photomask,developing, etc., by laser direct imaging, a pattern generator and thelike or, a combination of these methods) to produce apertures. In FIG.20( d), first material 122 (for example, a metal such as copper) hasbeen deposited into the apertures (for example, by electrodeposition) toa thickness substantially similar to that of material 117. In FIG. 20(e), a second layer of material 117 (or an alternative patternable moldmaterial) is deposited without stripping the first layer of material 117so that the first layer provides support for the second layer. It isassumed in the present embodiment that material 117 is a patternablemold material that may be patterned more than once.

In FIG. 20( f), the two layers of material 117 have been patterned toform apertures (including an aperture adjacent to first material 122)and to expose a top portion of first material 122. In FIG. 20( g), asecond material (for example, nickel) is deposited over the exposedareas of substrate 108 and first material 122. In FIG. 20( h), material117 is removed. In FIG. 20( i), a third material 124 (for example,silver) is blanket deposited over substrate 108, first material 122 andsecond material 123. In FIG. 20( j), the layer has been planarized to asufficient depth to establish a layer of the desired thickness,flatness, and surface finish.

Referring to FIGS. 21( a)-(i), a third exemplary embodiment is shown fordepositing more than two materials on the same layer wherein two or moredifferent materials (for example, metals) are adjacent to each other. InFIG. 21( a), a substrate 108 is shown, onto which patternable moldmaterial 117 (for example, photoresist or solder mask) has beendeposited as shown in FIG. 21( b). In FIG. 21( c), material 117 has beenpatterned (for example, if a photoresist, by use of a photomask,developing, etc., by laser direct imaging, a pattern generator and thelike or, a combination of these methods) to produce apertures. In FIG.21( d), first material 122 (for example, a metal such as copper) hasbeen deposited into the apertures (for example, by electrodeposition).

In FIG. 21( e), material 117 is patterned again to produce additionalapertures. It is assumed in the present embodiment that material 117 isa patternable mold material that may be patterned more than once. InFIG. 21( f), second material 123 (for example, a metal such as nickel)is deposited into the additional apertures (for example, byelectrodeposition). In FIG. 21( g), material 117 is removed. In FIG. 21(h), a third material 124 (for example, silver) is blanket deposited oversubstrate 108 and second material 123. In FIG. 21( i), the layer hasbeen planarized to a sufficient depth to establish a layer of thedesired thickness, flatness, and surface finish.

Thus, unlike in the second embodiment discussed above, according to thethird embodiment, a second layer of patternable mold material 117 is notused. Instead, the first layer of material 117 is patterned twice inorder to deposit two or more different materials that are adjacent toeach other on the same layer. As a result, the second-deposited materialdeposits over the first-deposited material, making the entire thicknessof deposit greater and more planarization necessary to achieve the finallayer thickness. In comparison, the second embodiment discussed above,where the second layer of mold material covers up much of thesecond-deposited material, reduces this overall thickness.

Referring to FIGS. 22( a)-(i), a fourth exemplary embodiment is shownfor including two or more different materials (for example, metals) thatmay be adjacent to each other on the same layer. In FIG. 22( a), asubstrate 108 is shown, onto which an ablatable material 125 isdeposited, as shown in FIG. 22( b). Ablatable material 125 may be anysuitable material that is ablatable by, for example, ultraviolet lasers.Examples of suitable ablatable materials include, but are not limitedto, polyimide, polyurethane, and the like. In FIG. 22( c), material 125is ablated to produce an aperture. In FIG. 22( d), first material 122(for example, a metal such as copper) has been deposited into theapertures (for example, by electrodeposition).

In FIG. 22( e), material 125 is again ablated to produce an additionalaperture adjacent to first material 122. Ablation of material 125adjacent to material 122 may slightly reduce the thickness of material122 if the radiation used for ablation overlaps material 122; however,by making material 122 thicker than the desired ultimate layerthickness, this can be tolerated. Moreover, by selecting the wavelengthand/or intensity of such radiation, selective ablation of material 125with little effect on material 122 may be achieved. In FIG. 22( f),second material 123 (for example, nickel) has been deposited (forexample, by electrodeposition) into the additional aperture and over theexposed portion of first material 122. Assuming a total of threematerials on this layer, material 125 can now be completely removed (forexample, by ablation) as shown in FIG. 22( g) and—as shown in FIG. 22(h), a third material 124 (for example, silver) can be blanket depositedover substrate 108, first material 122 and second material 123. In FIG.22( i), the layer has been planarized to a sufficient depth to establisha layer of the desired thickness, flatness, and surface finish.

According to some embodiments of the invention, multiple layers may bepatterned using a single plating step to build an expanding geometricalstructure 126 on a substrate 108 such as that shown in FIG. 23( a), or acontracting geometrical structure 127 on a substrate 108 such as thatshown in FIG. 23( b).

FIGS. 24( a)-(f) illustrate an embodiment of a process for forming theexpanding geometrical structure 126 shown in FIG. 23( a). In FIG. 24(a), a substrate 108 is shown, onto which patternable mold material 117(for example, photoresist or solder mask) has been deposited. Material117 is being exposed to light 128 (for example, ultraviolet) that ispreferably highly-collimated and which passes through photomask 129 inclear regions of the mask to produce exposed areas of patternable moldmaterial 117′.

When an expanding geometry like that shown in FIG. 23( a) is formed,some preferred embodiments of the invention use a negative patternablemold material, i.e. one that becomes insoluble to the developer in thoseregions exposed to light. By using a negative patternable mold material,precise exposure control is not required (i.e., precise control of depthof penetration of light 128, exposure time, and the like). This isbecause exposure of the current layer does not expose previouslyunexposed areas of the layers below it due to the dark area of mask 129.Other embodiments may use a positive resist and exercise preciseexposure control.

Succeeding layers of the structure 126 are exposed in a similar manner,as shown in FIGS. 24( b)-(d). In FIG. 24( e), the unexposed portion ofthe material 117 is removed. In FIG. 24( f), a single plating step isperformed which fills the pattern left by the removal of material 117′with a material 130 (for example, a metal). The patternable moldmaterial acts as a mold for forming structure 126. In FIG. 24( g), theexposed portions 117′ are removed, leaving structure 126.

FIGS. 25( a)-(g) illustrate an embodiment of a process for forming thecontracting geometrical structure 127 shown in FIG. 23( b). In FIG. 25(a), a substrate 108 is shown, onto which patternable mold material 117(for example, photoresist or solder mask) has been deposited. Material117 is being exposed to light 128 (for example, ultraviolet) that ispreferably highly-collimated and which passes through photomask 131 inclear regions of the mask to produce exposed areas of patternable moldmaterial 117′.

When an contracting geometry like that shown in FIG. 23( b) is formed,some preferred embodiments of the invention use a positive patternablemold material, i.e. one that becomes soluble to the developer in thoseregions exposed to light. By using a positive patternable mold material,precise exposure control is not required (i.e., precise control of depthof penetration of light 128, exposure time, and the like). This isbecause exposure of the uppermost layer does not expose previouslyunexposed areas of the layers below the uppermost layer due to the darkarea of mask 131. Other embodiments may use a negative resist andexercise precise exposure control.

Succeeding layers of the structure 127 are exposed in a similar manner,as shown in FIGS. 25( b)-(d). In FIG. 25( e), the exposed portion of thematerial 117 is removed. In FIG. 25( f), a single plating step isperformed which fills the pattern left by the removal of material 117′with a material 132 (for example, a metal). The patternable moldmaterial acts as a mold for forming structure 127. In FIG. 24( g), theexposed portions 117′ are removed, leaving structure 127.

According to other embodiments of the invention, both the expandinggeometric structure and the contracting geometric structure processesdescribed above may develop the patternable mold material after eachexposure. In this case, preferred embodiments may use a dry film resistas the patternable mold material. The dry film resist is used such thatthe resist will “tent” over apertures formed in the layers.

According to some embodiments of the invention, when multiple layers arepatterned using a single plating step, a seed layer may first bedeposited before the plating step if an angle (such as the exemplaryangle 133 shown in FIG. 26) is above a critical angle 133. As shown inthe flowchart of FIG. 27, some embodiments of the invention may analyzefeatures on a layer (S2701) to determine whether any angle of a featureis above a critical angle (S2701). If an angle of a feature is not abovethe critical angle, no seed layer will need to be deposited (S2703).However, if the angle is above the critical angle, a seed layer willneed to be deposited (S2704) to ensure that material can be plated overthe mold material (by ‘mushrooming’ in some cases). The angle analysismay be performed, for example, by a suitable processing device running asuitable software program, or may be performed by hardware, firmware ora combination thereof.

Referring now to FIG. 5( bb), carrier 1 and all that is attached to ithas been placed on a fixture such that pins 93 enter into holes 15. Inaddition, material 59 has been removed (for example, by dissolution). InFIG. 5( cc), material 23 has been melted (preferably by activation ofelements 17) such as to release substrate 25. Alternatively, material 23may also be removed chemically. In FIG. 5( dd), carrier 1 has beenpushed down further onto pins 93 such that substrate 25 is entirely freeof carrier 1 and material 31 has either delaminated from carrier 1 orhas become torn as shown. The spaces left by the removal of material 59enables easier delamination of the carrier 1 because there is no buildupof the layer materials in the space occupied by material 59.

In FIG. 5( ee), substrate 25 has been removed from the carrier 1 andplaced on support 93 (for example, dicing tape). In FIG. 5( ff), kerfs95 have been cut through all deposited materials as well as throughsubstrate 25 to singulate individual portions of substrate 25 intoindividual die. According to other embodiments, the kerfs may be cutprior to removal of substrate 25 from carrier 1. Such kerfs may be cut,for example, by resin or metal-bonded diamond dicing saw blades, bytoothed dicing saw blades, or by using a laser or high-pressure fluidjet. Scrap die 99, including regions of structural materials such as 79,no longer connect to die 97 and may now be separated from die 97.

In FIG. 5( gg), materials 63, 89, and 92 have been removed (for example,by chemical dissolution selective to materials 65, 91, and 94. In FIG.5( hh), material 31 has been removed using a timed etching step suchthat it is removed from most of substrate 25 but remains substantiallyunder features of material 65, though with some undercutting 100 of saidfeatures. Finally, in FIG. 5( ii), support 93 has been removed from die97, and die 97 have been separated from one another. If desired, theseremoval processes may be performed prior to dicing substrate asdescribed above.

In previously described embodiments, the alignment targets may beattached to a carrier to which the EFAB substrate is affixed. Otherembodiments of the invention provide methods of providing alignmenttargets in the substrate itself, in case a carrier is not used, or thecarrier is not sufficiently large relative to the substrate, or it isnot desired to incorporate the targets in the carrier for other reasons.According to some embodiments of the invention, the targets can belocated in a variety of locations on the substrate. For example, thetargets may be located in unused die sites, near the edge of the waferoutside the functional die, in the dicing lanes, and the like.

As in the previous embodiments, the embodiments described below alignall newly-added layers again and again to the same alignment targetsrather than align each new layer to an alignment target formed in theprevious layer. However, according to these embodiments, the alignmenttargets are located on the substrate rather than on the carrier, as inthe previously described embodiments. Aligning to targets on thesubstrate or carrier instead of to targets in the previous layer avoidsthe accumulation of errors, including the error produced by alignmenttargets on each new layer not being identical in shape or size to thatof others on previous layers.

According to some embodiments of the invention, as shown in FIGS. 29(a)-(x), the targets may be formed by electrodepositing or otherwisedepositing material onto the substrate (for example, by sputtering). Thetargets may also be formed using lift-off approaches, etching and thelike. The targets are then covered with a dielectric material so as toavoid plating over them (which would obscure the targets as layers areadded). FIG. 29( a) shows a substrate 150 which has been coated with apatternable mold material 151 (for example, a photoresist) in FIG. 29(b). In FIG. 29( c), material 151 has been patterned to form aperturessuch as 152 into which material 153 is then deposited (for example, bysputtering, vacuum deposition, electrophoretic deposition, and the like)as shown in FIG. 29( d) to form targets 154 as shown in FIG. 29( e).

In FIG. 29( e), material 151 has been removed. In FIG. 29( f), a resistor other patternable material 155 has been applied and in FIG. 29( g)material 155 has been patterned to form an aperture 156 wider than andfully including target 154. Aperture 156 is made large enough such that‘mushrooming’ of deposited materials which might occur while formingsubsequent layers of the electrochemically-fabricated device cannotoptically obscure targets 154. In FIG. 29( h), dielectric material 157has been deposited into aperture 156 and non-adherent material 158 (forexample, Teflon®, SYTOP® or parylene) has preferably been deposited ontop of dielectric material 157 (if material 157 is itself non-adherentmaterial 158 may be omitted).

According to some embodiments of the invention, the total thickness ofmaterials 157 and 158 may be made small enough that neither may comeinto contact with the lapping or polishing plate during planarization ofthe first layer and therefore will not be damaged or altered; this isthe approach assumed in FIG. 29. Alternatively, material 158 (ormaterial 157 if material 158 is not used) may be deposited to athickness that ensures that it will be lapped and/or polished (forexample, along with the first layer of the electrochemically-fabricateddevice). The planarization operation then would be performed so as toprovide an optically smooth and transparent surface.

If materials 154, 157, and 158 are not electrodeposited, portions ofthese materials would also be deposited onto materials 151 and 155,respectively, but these would be removed upon removal of materials 151and 155 (for example, during a lift-off process). Also note thatmaterials 154, 157, and 158 might also be deposited in a blanket fashionand then patterned using etching (for example, using a photoresist).

In FIG. 29( i), material 155 has been removed and fully-encapsulated,non-conductive, non-adherent alignment target 154 remains behind. TheEFAB process can now begin. The remaining FIGS. 29( j)-(r) assume anEFAB process based on photoresist or other adherent patternable material(hereinafter assumed to be resist). However, embodiments they areequally applicable to an EFAB process using an INSTANT MASK™.

In FIG. 29( j), resist 159 has been applied. In FIG. 29( k), resist 159has been patterned to produce apertures 160. In FIG. 29( l), material161 has been electrodeposited into apertures 160, and in FIG. 29( m)resist 159 has been stripped. In FIG. 29( n) material 162 has beenelectrodeposited onto the substrate, filling the apertures left behindby the removal of resist 159, and not depositing over material 158 dueto its insulating nature. However, due to the ability of electrodepositsto ‘mushroom’ over the edges of insulators, material 162 slightlyoverlaps the edges of material 158 as shown. In FIG. 29( o), the layerof materials 161 and 162 has been planarized (in the case shown, theplanarization plane is above the surfaces of materials 157 and 158),completing the first EFAB layer.

In FIG. 29( p), resist 159 has been applied to the first layer and inFIG. 29( q) regions of resist 159 have been removed mechanically(especially for dry film resist) or by chemical stripping (for any typeof resist) to form windows 163. According to some embodiments of theinvention, if electrodeposited resist is used, targets 154 (since theyare coated with at least one insulating material) will not accumulateresist and thus no removal of resist covering targets 154 is required.In some embodiments, mechanical removal might involve use of a punch orcutting blade, possibly combined with a vacuum or mechanical tweezers toextract loosened pieces, especially of dry film resist. The non-adherentnature of material 158 helps in this removal process, especially for dryfilm resist. According to some embodiments, resist 159 may be applied soas not to fill in windows 163. According to other embodiments, resist159 may be left filling windows 163, if it is sufficiently transparentand non-distorting to not have a detrimental effect on targets 154.

Referring to FIG. 29( r), photomask 164 has been aligned to targets 154visible through windows 163 and resist 159 is exposed to UV light 165.In FIG. 29( s), resist 159 is developed to yield apertures which arethen electrodeposited with material 161 in FIG. 29( t). At this time,material 161 is also deposited slightly over material 158 to form amushroomed region 166, slightly reducing the size of windows 163. InFIG. 29( u), material 162 has been deposited and materials 161 and 162have been planarized to yield the second EFAB layer. Material 162 hasbeen deposited over region 166, further reducing the size of windows 163and forming a mushroomed region 167. It should be noted the none of theFIGS. are to scale and that normally electrodeposited material mushroomsmuch more isotropically than is shown in the FIGS.

In FIG. 29( v), resist 159 has been applied to the second layer and inFIG. 29( w) regions of resist 159 have again been removed so as not tocover windows 163. Finally, in FIG. 29( x), materials 161 and 162 havebeen deposited as with previous layers, again using windows 163 to allowalignment between photomask targets and targets 154. Also, materials 161and 162 have been planarized to yield the third EFAB layer. Materials161 and 162 have formed mushroomed regions 168 and 169, respectively,further reducing the size of windows 163. Additional layers can be builtin a similar fashion, preferably continuing to use targets 154 foralignment so long as they are not obscured by mushroomed regions ofdeposited materials.

In a variation of the embodiment shown in FIGS. 29( a)-(x), material 153may be the same as material 161 or 162 and the two deposited together(however, material 161 or 162 in the region of targets 154 needs to bedeposited to a lower height so that it is below the planarization planefor the first layer. In another variation of this embodiment, materials157 and 158 may be solid materials (for example, Teflon®-coated glass)that are placed over targets 154 and secured (for example, by gluing orby the mushrooming effect of subsequent plating). According to someembodiments of the invention, such solid material may intentionally beplanarized to establish a smooth optical surface reasonably parallel tosubstrate 150 if desired. In another variation of this embodiment,targets 154 may be formed by etching features into substrate 150 in lieuof by depositing material 153.

FIGS. 30( a)-(r) illustrate another embodiment of the invention, whichcan be used with dielectric substrates or else with metal substrates onwhich the area of the alignment target is insulating or is covered withan insulating material. In this embodiment, the alignment targets areformed, for example, in the adhesion and/or seed layers (for example, Tiand Au, respectively) that coat the dielectric substrate, and thetargets are electrically isolated from the surrounding metal layers byan insulating gap so that they are not able to be plated onto.

FIGS. 30( a)-(r) assume the alignment targets are patterned using alift-off approach, but other approaches may be used in otherembodiments. Etching of blanket-deposited adhesion and/or seed layersusing a photoresist or similar material is one such approach. Anotherapproach is to plate the targets on top of the adhesion and/or seedlayers and then etch these layers back using a time-controlled etch suchthat the material of the plated targets avoids excessive undercutting ofthe adhesion and/or seed layers.

Dielectric substrate 170 shown in FIG. 30( a) is covered with resist 171(FIG. 30( b)) which is patterned (FIG. 30( c)), preferably withsidewalls having a negative slope (undercut), as is the norm in lift-offpatterning. In FIG. 30( d) metal(s) have been deposited to form anadhesion/seed layer 172. In FIG. 30( e) resist 171 has been removed,leaving patterned layer 172. The patterning operation both patternsalignment targets 173 and disconnects them electrically from theremainder of the layer 172.

FIG. 31 shows a top view of substrate 170, layer 172, and targets 173.The bare area of substrate 170 surrounding targets 173 is made largeenough such that ‘mushrooming’ of deposited materials while formingsubsequent EFAB layers cannot optically obscure targets 173. Even if dryfilm resist is used in subsequent processing, this is likely to becomelaminated to the alignment target in making the first few layers, sincethe distance to the target is small. Therefore, in some embodiments,targets 173 may be coated with a non-adherent material (not shown)similar to that described above so that resist applied over them can beeasily removed.

Referring to FIG. 30( f) resist 174 has been applied to pattern thefirst EFAB layer. In FIG. 30( g) resist 174 has been patterned toproduce apertures and in FIG. 30( h) material 175 has beenelectrodeposited into these apertures. In FIG. 30( i), resist 174 hasbeen stripped and in FIG. 30( j) material 176 has beenblanket-deposited. A mushroomed region 177 has been produced alongsidethe patterned edge of layer 172.

In FIG. 30( k), materials 175 and 176 have been planarized to yield thefirst EFAB layer. In FIG. 30( l), resist 174 (dry film resist is assumedin the figure, ‘tenting’ over targets 173) has been applied to the firstlayer. In FIG. 30( m), the portion of resist 174 over targets 173 hasbeen removed mechanically (especially for dry film resist) or bychemical stripping (for any type of resist) to form windows 179. Inembodiments wherein electrodeposited resist is used, targets 173 (sincethey are electrically isolated) will not accumulate resist and thus noremoval of resist covering targets 173 is required. In some embodiments,mechanical removal might involve use of a punch or cutting blade,possibly combined with a vacuum or mechanical tweezers. According tosome embodiments of the invention, resist 174 may be applied so as notto fill in windows 179. In some embodiments, resist 174 may also be leftfilling windows 179, if it is sufficiently transparent andnon-distorting to not have a detrimental effect on targets 173.

In FIG. 30( n), resist 174 is patterned by using targets 173 foralignment. In FIG. 30( o), material 175 has been deposited. A mushroomedregion 178 has been produced alongside the edge of the first layer,surrounding targets 173.

In FIG. 30( p), resist 174 has been stripped and in FIG. 30( q) material176 has been blanket deposited. A mushroomed region 180 has beenproduced over mushroomed region 178. In FIG. 30( r) materials 175 and176 have been planarized. Additional layers can be built in a similarfashion, preferably continuing to use targets 173 for alignment.

The methods of the above embodiments can also be used to incorporate ahuman and/or machine-readable identification code (e.g., a bar code orthe like) into the surface of the substrate as a method of identifyingthe substrate, particularly one that is not attached to a carrierbearing an identifying tag. This can be done in the same manner as, andalong with, alignment targets that are incorporated as described above,such that deposition of material is substantially prevented fromoccurring above the identification code and obscuring it from view.

In a variation of the embodiments shown in FIGS. 29 and 30, the targetsmay be covered by a solid material (for example, a light tack tape suchas dicing tape) or ‘plug’ to protect the targets from contact with theresist and allowing the resist to easily be removed from the targetswithout leaving any residue behind.

FIGS. 59( a)-(i) show a further embodiment of the invention for forminga target on a substrate. As shown in FIG. 59( a), a substrate 400 isshown, onto which a adhesion/seed layer 402 has been deposited as shownin FIG. 59( b). In FIG. 59( c), patternable mold material 404 (forexample, a photoresist) has been deposited. In FIG. 59( d), patternablemold material 404 has been patterned to form apertures. In FIG. 59( e),portions 406(a) and 406(b) comprised of a first material 406 (forexample, nickel) have been formed in the apertures. Portion 406(a) willbe a target, while 406(b) will be a device or structure.

In FIG. 59( f), a second material has been blanket deposited overadhesion/seed layer 402 and 406(a) and 406(b). In FIG. 59( g),planarization has been performed. In FIG. 59( h), second material 408surrounding portion 406(a) has been removed, for example by localetching, leaving only the adhesion/seed layer 402 around portion 406(a).In FIG. 59( i), the adhesion/seed layer 402 around portion 406(a) hasbeen removed, for example, by local etching.

Thus, the embodiment for forming a target on a substrate described abovefirst forms a layer of materials on an adhesion/seed layer. Then, atleast one of the materials and the adhesion/seed layer is removed toelectrically isolate the target by forming an island of non-conductivematerial around the target. In this manner, the target will not beplated onto during a subsequent plating process. According to someembodiments of the invention, an additional etching and/or polishingstep may be performed on the nickel to remove any smearing or scratchingthat may have resulted from the planarization step.

In previously described embodiments, the alignment targets may beattached to a carrier to which the EFAB substrate is affixed or to anEFAB substrate. Yet other embodiments of the invention provide methodsof providing alignment targets in the previous layer for alignment of aphotomask to the previous layer. After a layer consisting of structuraland sacrificial materials is formed, there may be difficulty in forminghigh-quality targets because of, for example, smearing of one materialinto another, poor contrast between various materials (e.g., structuraland sacrificial) in the layer, and/or surface roughness. These problemsmay result from planarization and may be more acute if two or morematerials on the layer are close in color. When these problems exist, itmay be difficult for a machine vision system (or operator) to identifyand accurate locate the targets.

Thus, according to some embodiments of the invention, etching of thearea of the targets may be performed to enhance the contrast. Otherembodiments may also or in the alternative, polish the area of thetargets to remove scratches and smear due to the planarization step. Insome cases, the effects of planarization on different targets may bedependent, for example, on a particular target's location on the layer.For example, one target located in a particular area of the layer may bemore detrimentally affected by planarization than another target in adifferent location of the layer. Thus, according to some embodiments ofthe invention, multiple alignment targets may be located on the layer inorder that, for example, the more detrimentally affected targets may berejected or an average position calculated from among multiple targets.

As stated above, some embodiments of the invention may align a mask to aprevious layer based on targets located in the previous layer. Anexemplary shape of a target that may be located on a previous layer isshown in FIG. 32( a). An exemplary shape that may be used on a mask toalign to the target is shown in FIG. 32( b). FIG. 32(c) shows the shapesof FIGS. 32( a) and 32(b) as they would appear with proper alignment ofthe mask to the previous layer.

Some embodiments of the invention provide masks that include both shapesthat are used to align the photomask to a target on a previous layer(“alignment shapes”) and shapes that are used to form new targets on thelayer currently being patterned (“new target shapes”) in preparation foralignment of the subsequent layer.

Referring to FIGS. 33( a)-(d), some embodiments of the invention provideodd and even layer masks that have alternating patterns of alignmentshapes and new target shapes. FIG. 33( a) shows a first mask (Mask 1)having shapes that are used to form new targets on a first layer (layer1). Also shown in FIG. 33( a) is a first layer (Layer 1) showing acompleted two-material layer after patterning of the first materialusing Mask 1.

FIG. 33( b) shows a second mask (Mask 2) having both alignment shapesused to align the photomask to the targets previously patterned on thefirst layer and new target shapes for forming new targets on a secondlayer (Layer 2). Layer 2 also shows the layer produced using Mask 2. Itcan be seen that when the alignment shapes on the second mask areproperly aligned with the targets to be patterned on the first layer,new targets may also be formed on the second layer using the new targetshapes on the second mask.

FIG. 33( c) shows a third mask (Mask 3) having both alignment shapesused to align the photomask to the targets previously patterned on thesecond layer and new target shapes for forming new targets on a thirdlayer (Layer 3). Layer 3 also shows the layer produced using Mask 3. Itcan be seen that when the alignment shapes on the third mask areproperly aligned with the targets to be patterned on the second layer,new targets may also be formed on the third layer using the new targetshapes on the third mask.

FIG. 33( d) shows a fourth mask (Mask 4) having both alignment shapesused to align the photomask to the targets previously patterned on thethird layer and new target shapes for forming new targets on a fourthlayer (Layer 4). Layer 4 also shows the layer produced using Mask 4. Itcan be seen that when the alignment shapes on the fourth mask areproperly aligned with the targets to be patterned on the third layer,new targets may also be formed on the fourth layer using the new targetshapes on the fourth mask. In addition to alignment shapes and newtarget shapes, masks may contain vernier-type shapes to allow theaccuracy of alignment to be evaluated. The positions of such shapeswould also change from even to odd layers on alternating masks.

It may be desirable to reduce the number of photomasks required to builda structure through methods of mask minimization already described inU.S. Pat. No. 6,027,630. The method described in this patent for reusingphotomasks may be modified according to some embodiments of theinvention using software algorithms such that an existing or plannedphotomask for an even layer can be used in lieu of generating a newphotomask for an even layer, but not for an odd layer, and vice-versa,in the case that alignment targets, verniers, or other alternatingstructures are needed as described above.

Generally, a photomask is used to build structures across an entiresubstrate. However, there may be cases (e.g., the fabricate of prototypequantities) where only a quarter or a half of the substrate is neededfor the structures. For example, it may be desirable to build a multiplelayer structure while only using, for example, one quarter or one halfof the substrate. Conventionally one might choose to build on a smallersubstrate and perhaps use smaller (and less costly) photomasks as aresult. However, this approach requires specialized tooling and possiblyequipment for processing a substrate of smaller size, and does notensure that the processing conditions and thus behavior of the devicesproduced on the smaller substrate will be identical to those produced(typically in larger quantity) on the larger substrate. Conventionally,a different photomask may be necessary for each layer of the structure,adding significantly to the cost of fabricating the structure, even ifonly a small quantity of devices are needed.

In order to reduce the cost involved in using multiple photomasks,particularly when producing small or prototype quantities, someembodiments of the invention advantageously place multiple patterns(each pattern for exposing a different layer of the same structurelocated on some portion of the substrate) onto a single photomask.

Referring to FIG. 34( a), according to some embodiments of theinvention, substrate 134 is shown as having four quadrants 135, 136, 137and 138. The two arrows shown in quadrant 135 of substrate 134 representan particular orientation of a layer to be exposed. The X in theremaining quadrants 136, 137 and 138 represents a “don't care”condition. In other words, the only portion of the substrate 134intended to yield usable structures is quadrant 135.

Referring to FIG. 34( b), according to some embodiments of theinvention, photomask 139 is also shown as having four quadrants 140,141, 142 and 143, each having two arrows that represent a pattern havinga particular orientation. Each of quadrants 140-143 are used to exposean individual successive layer of a structure that is to be fabricatedin quadrant 135 of substrate 134. Also, each quadrant is shown with anumber 1-4 representing the order in which the photomask is applied forfour individual successive layers to be exposed in quadrant 135.

When the photomask 139 is used to expose the layers in quadrant 135,quadrant 140 (1) of the photomask is used in patterning the first of thefour successive layers. This is because quadrant 140 has the pattern onthe photomask that is initially in the correct orientation relative toquadrant 135 of substrate 134.

Then, according to some embodiments of the invention, the photomask 139is rotated (in this example, counterclockwise) by 90 degrees, such thatthe pattern in quadrant 141 (2) is in the correct orientation relativeto quadrant 135 of substrate 134. The photomask is then used to patternthe second of the four successive layers.

The same process is repeated for quadrants 142 (3) and 143 (4) in orderto pattern the third and fourth of the four successive layers,respectively. It is apparent from FIGS. 34( a)-(b) that the “don't care”quadrants 136, 137 and 138 will have no value since the layers will notbe in the correct thickness and moreover (if different layers arefabricated with different thicknesses) will not necessarily have thecorrect thicknesses. However, generally speaking, substrates such assubstrate 134 are less costly than a set of photomasks such as photomask139. Thus, even though a portion of the substrate 134 is not used, theeconomical use of the photomask leads to an overall cost savings for thefabrication process.

Although the embodiment described above divided the substrate and thephotomask into quadrants, other embodiments may divide the substrate andthe photomask into halves, with half of the substrate yielding usablestructures. In this case, two layers could be patterned using thephotomask, with a 180 degree rotation of the photomask being performedafter the first layer is patterned and before patterning the secondlayer. Other embodiments may use other divisions of the substrate andphotomask, with appropriate rotation and/or translation in anappropriate direction after each successive layer.

When using the above embodiments it may be desirable to cut thesubstrate so as to remove the “don't care” quadrants or “don't care”half prior to releasing the structures; otherwise corrupted structuresin these quadrants may become detached from the substrate while in theetchant bath and become entangled with or otherwise damage the desiredstructures. In some embodiments the photomask quadrants or halves maynot be used successively (i.e., quadrants 140-143 used to pattern layersin strict sequence).

If it is desired to fabricate more than a single quadrant or half of asubstrate that yields usable structures, the above embodiments can bemodified by incorporating a secondary mask which blocks light frompassing through the photomask in some regions, and performing multipleexposures for each layer. For example, if the photomask is divided intoquadrants, the secondary mask would normally be designed so as toprevent three out of four of the substrate quadrants from being exposed.The secondary mask would then be rotated in synchronization with thephotomask, and up to three more exposures would then be made, thusexposing more of substrate completely to the correct pattern for a givenlayer (structures would be oriented differently depending on whichsubstrate quadrant they were located in).

More generally, the embodiments described above may be used to reducethe number of photomasks required, with a more arbitrary assignment ofphotomask quadrants to device layers (e.g., quadrant 140 patterninglayer 6, quadrant 141 patterning layer 2, etc.). However, it may stillbe necessary to pay attention (due to the need for alignment shapes andtarget shapes in particular locations) to which layer patterns are inwhich quadrants. For example, instead of placing the patterns for layers1, 2, 3, and 4 on a first photomask and the patterns for layers 5, 6, 7,and 8 on a second photomask, one might put the patterns for layers 1, 4,7, 2 (in that order of clockwise or counterclockwise rotation) on thefirst photomask and the patterns for 3, 8, 5, 6 (in that order) on thesecond photomask: such an arrangement would preserve the layout of even-and odd-numbered layer patterns.

In addition, although the embodiment described above used photoresist asan example of a patternable mold material, the embodiments discussedabove would also be applicable to INSTANT MASKS™ and other suitablepatternable mold materials. Also, although the embodiment describedabove rotated the photomask while the substrate remained fixed, areverse process is also possible, i.e., the substrate may be rotated asuitable amount (for example, 90 degrees) while the photomask remainsfixed.

According to some embodiments of the invention, additional alignmenttargets are used in proportion to the number of rotations required.Using these additional alignment targets, some embodiments of theinvention as described below allow multiple odd and even layers to bepatterned using a single mask by rotating of the mask to producealternating layouts of alignment shapes and new target shapes.

As an example, FIG. 35( a) shows photomask 139 from FIG. 34( b) ashaving four quadrants with 90 degree differences in orientation asdescribed above. Each of quadrants 140-143 are used in patterning anindividual successive layer of a structure that is to be fabricated inquadrant 135 of substrate 134. Also, each quadrant is shown with anumber 1-4 representing the order in which the photomask is applied forfour individual successive layers to be patterned in quadrant 135.

In FIG. 35( b), photomask 139 is also shown as having two pairs ofalignment shapes used to align the photomask to the targets on aprevious layer on substrate 134 and two pairs of new target shapes forforming new targets on the layer currently being patterned on substrate134.

As discussed above, according to some embodiments of the invention, afirst quadrant 140 of photomask 139 is used in patterning a first layerin quadrant 135 of substrate 134. It is assumed in the presentembodiment that a layer formed previous to the current layer to bepatterned included alignment targets that may be aligned with alignmentshapes 182 and 183. According to some embodiments of the invention,during the same patterning step, new target shapes 184 and 185 are usedin patterning new targets in the layer currently being patterned inquadrant 135.

After patterning the layer having the pattern of quadrant 140 ofphotomask 139, photomask 139 may be rotated a particular amount anddirection (90 degrees in a counterclockwise direction in the currentembodiment) such that the pattern in quadrant 141 (2) is in the correctorientation relative to quadrant 135 of substrate 134 in order topattern a succeeding layer in quadrant 135, as illustrated in FIG. 35(b). FIG. 35( b) shows the position of photomask 139 relative tosubstrate 134 after such rotation. Alignment shapes 188 and 191 may nowbe aligned with the targets formed on the previously patterned layer bynew target shapes 184 and 185. According to some embodiments of theinvention, during the same patterning step, new target shapes 189 and190 are used to pattern new targets in the layer currently beingpatterned in quadrant 135. It should also be noted that other pairs ofalignment shapes and target shapes are available 90 degrees from thosediscussed above and these may also be used for alignment if accessibleto the mask aligner.

Thus, it can be seen that some embodiments of the invention as describedabove allow multiple odd and even layers to be patterned using a singlemask wherein rotation of the mask produces alternating patterns ofalignment shapes and new target shapes, thus resulting in a reduction inthe number of photomasks required to produce structures and acorresponding reduction in the cost of fabrication. In the case in whichtwo patterns (vs. four) are incorporated into the photomask and a 180degree (vs. 90 degree) is used, the alignment shapes and target shapeswould be positioned typically symmetrically about the centerline of themask as shown in the photomask of, for example, FIG. 33( b). Rotation by180 degrees of such a photomask relative to the substrate wouldautomatically create the alignment shapes and target shape layout of,for example, FIG. 33( c).

According to other embodiments of the invention, mask usage may beminimized through using both a single photomask to expose a layer and,in addition, using laser direct imaging, a pattern generator or othersuitable means for modifying the exposure that has or will be performedusing the photomask. In this manner, for example, an initial pattern forforming a desired final feature—but varying slightly from the desiredfinal feature—may be initially patterned in a patternable mold materialusing only a single photomask. Then, the initial pattern may be slightlymodified using, for example, laser direct imaging to produce the desiredfinal feature. According to some embodiments of the invention, ananalysis may be performed, for example, on a layer by layer basis todetermine areas on a layer where such modification techniques would bepossible and desirable in lieu of creating a new mask in order toachieve the desired pattern of exposure. This analysis may be performed,for example, by a suitable processing device running a suitable softwareprogram, or may be performed by hardware, firmware or a combinationthereof.

According to further embodiments of the invention, foreign objects maybe incorporated within layers formed on a substrate. Examples of foreignobjects may include, but are not limited to, ball bearings, integratedcircuits, lenses, mirrors, fiber optic strands, needle probes or otherobjects that cannot easily be manufactured during an EFAB process due togeometry limitations or materials limitations.

FIGS. 37( a)-(p) show a process for incorporating objects within layersformed on a substrate, according to some embodiments of the invention.As shown in FIG. 37( a), a substrate 202 is shown, onto whichpatternable mold material 204 (for example, photoresist or solder mask)has been deposited as shown in FIG. 37( b). In FIG. 37( c), material 204has been patterned (for example, if a photoresist, by use of aphotomask, developing, etc., by laser direct imaging, a patterngenerator and the like or, a combination of these methods) to produceaperture 201. In FIG. 37( d), one or more objects 206 (in the presentexample objects 206 are balls) are made to fall into aperture 201, forexample by flowing the objects 206 onto the surface 203 of patternablemold material 204, for example in a liquid medium. According to otherembodiments, where objects 206 are balls or other spherical objects, theobjects may be rolled onto the surface 203. Alternatively, objects 206may be poured onto the surface 203, and those objects not falling intoan aperture may be squeegeed off the surface 203 or otherwise removed asshown in FIG. 37( e). Other embodiments may use other methods forplacing objects 206 into apertures such as aperture 201. For example, apick and place machine or other suitable machine may be used to placethe objects into the apertures.

In FIG. 37( f), another patternable mold material 208 has been depositedin order to cap the object 206, i.e., to secure object 206 withinaperture 201. According to some embodiments, material 208 may be a dryfilm resist. According to other embodiments, patternable mold material208 may be the same type of material as patternable mold material 204 orsome other suitable patternable mold material. According to someembodiments, forming patternable mold material 208 over object 206 maybe unnecessary if, for example, sufficient care is used such that theobject 206 does not fall out of aperture 201.

In FIG. 37( g), patternable mold material 208 has been patterned toproduce aperture 205. In FIG. 37( h), a first material 210 (for example,a metal such as copper) has been formed (for example byelectrodeposition through aperture 205) in aperture 201 to at leastpartially encase and secure the object 206 within aperture 201. Firstmaterial 210 is a sacrificial material, according to the embodiment ofthe invention shown in FIG. 37. In FIG. 37( i), patternable moldmaterial 204 has been removed (for example, by use of a chemicalstripper) to expose regions of the substrate 202 which are not coveredwith first material 210. In FIG. 37( j), a patternable mold material 212has been deposited over substrate 202 and material 210. Patternable moldmaterial 212 may be, for example, a dry film resist or a suitable liquidresist.

In FIG. 37( k), patternable mold material 212 has been patterned toproduce apertures 207 and 209. First material 210 is then deposited intoapertures 207, 209, as shown in FIG. 37( l). Although according to thepresent embodiment first material 210 is deposited as shown in FIG. 37(l), according to other embodiments a material different from firstmaterial 210 (for example, a different metal) may be deposited instead.In FIG. 37( m), patternable mold material 212 has been stripped. In FIG.37( n), second material 214 has been blanket deposited (for example byelectrodeposition) to fill apertures 207, 209. Second material 214 maybe a material different from first material 210 (for example, adifferent metal).

In FIG. 37( o), materials 210 and 214 have been planarized to asufficient depth to remove all of second material 214 overlying firstmaterial 210, and also to establish a layer of the desired thickness,flatness, and surface finish. As shown in FIG. 37( o), the level ofplanarization 211 may be set to be above the upper level of object 206.Alternatively, in other embodiments, it may be desirable to planarize tosome level below the upper level of object 206. In that case, an upperportion of the object itself may be planarized.

FIG. 37( p) shows an exemplary product of the above-described processafter additional layers have been formed on the substrate 202 and firstmaterial 210 has been removed, according to some embodiments of theinvention. Thus, as shown in FIG. 37( p), multiple layers of secondmaterial 214 remain to form a structure on substrate 202 that has object206 incorporated in a layer of the structure.

FIGS. 38( a)-(p) show another embodiment of the invention forincorporating foreign objects within layers formed on a substrate. Theexemplary process shown in FIGS. 38( a)-38(c) and 38(h)-38(p) areidentical to the corresponding process steps shown in FIGS. 37( a)-(c)and 37(h)-(p) and described above. Thus, these process steps will not bedescribed further. The exemplary process shown in FIG. 38 differs fromthat shown in FIG. 37 only as shown in FIGS. 38( d)-(g), as will bedescribed below.

As shown in FIG. 38( d), after aperture 201 is formed in patternablemold material 204, a second patternable mold material 216 is formed overpatternable mold material 204 and aperture 201. Patternable moldmaterial 216 may be, for example, a photoresist that is deformable.According to some embodiments, patternable mold material 216 maypreferably be an elastic or semi-elastic material. In FIG. 38( e),aperture 213 is formed in patternable mold material 216. In FIG. 38( f),objects 206 are flowed or otherwise deposited onto the surface 203patternable mold material 216.

In FIG. 38( g), one or more objects 206 are forced into aperture 201through the aperture 213 formed in the deformable patternable moldmaterial 216 and remains secured in the aperture by patternable moldmaterial 216. Thus, some embodiments of the invention as shown in FIG.38 differ from those shown in FIG. 37 in that the second layer ofpatternable mold material 216 is formed before objects 206 areincorporated into a layer and an object 206 is inserted through anaperture 213 formed in the patternable mold material 216 into aperture201.

FIG. 39 shows a top view of a step in the formation of a ball bearingstructure formed according to some embodiments of the invention. FIG. 39shows patternable mold material 218 formed over apertures 215 to secureballs 220 within the apertures 215. Patternable mold material 218 hasbeen patterned to include stripes 217 that prevent the balls 220 fromfalling out of apertures 215, but allow deposition of a material intoapertures 215 on either side of stripes 217. FIG. 40 shows a completedball bearing structure formed according to some embodiments of theinvention. Balls 220 move freely in a track 222 that is formed betweeninner structural material 224 and outer structural material 226.

FIGS. 41( a)-(k) show another embodiment of the invention forincorporating foreign objects within layers formed on a substrate. Asshown in FIG. 41( a), a substrate 228 is shown, onto which patternablemold material 230 (for example, photoresist or solder mask) has beendeposited as shown in FIG. 41( b). In FIG. 41( c), material 230 has beenpatterned (for example, if a photoresist, by use of a photomask,developing, etc., by laser direct imaging, a pattern generator and thelike or, a combination of these methods) to produce apertures 219 and221. In FIG. 41( d), a first material 232 (for example, a metal such ascopper) has been formed (for example by electrodeposition) in apertures219, 221. In FIG. 41( e), patternable mold material 230 has beenstripped. In FIG. 41( f), a patternable mold material 234 has beenformed over first material 232. Patternable mold material 234 may be,for example, a dry film resist or a suitable liquid resist.

In FIG. 41( g), patternable mold material 234 has been patterned toexpose areas of substrate 228 and first material 232. In FIG. 41( h), asecond material 236 (for example, a metal such as nickel) has beenformed (for example by electrodeposition) on the exposed areas ofsubstrate 228 and first material 232. In FIG. 41( i), patternable moldmaterial 234 has been removed (for example, by use of a chemicalstripper), leaving a cavity 223. In FIG. 41( j), materials 232 and 236have been planarized to a sufficient depth to remove all of secondmaterial 236 overlying first material 232, and also to establish a layerof the desired thickness, flatness, and surface finish. In FIG. 41( k),object 238 has been placed inside cavity 223.

Thus, it can be seen that according to the embodiment of the inventiondescribed above, a cavity is created by patterning two layers ofpatternable mold material. First, a layer of patternable mold materialis patterned for the deposit of the first material. The first materialis deposited. The first patternable mold material is removed to form acavity. Then, a second layer of patternable mold material is formed andpatterned for the deposit of the second material. The second layer ofpatternable mold material protects the cavity from deposition of thesecond material. The second material is then deposited, and the secondlayer of patternable mold material is removed. The object is then placedin the cavity. Although the object is shown as being placed into thecavity after the formation of a first layer according to someembodiments of the invention, other embodiments may form additionallayers while maintaining the cavity. Once the desired number of layershas been formed or at some intermediate point in the formation oflayers, the object may be inserted in the cavity. According to someembodiments of the invention, additional material may be deposited overthe object to secure it in place; if desired the layer may be planarizedagain after this deposition step. According to some embodiments of theinvention, first material 232 may be a sacrificial material while secondmaterial 236 may be a structural material. In other embodiments, thereverse may also be true. When first material 232 is the sacrificialmaterial, etching efficiency of the sacrificial material may be improveddue to the sacrificial material being adjacent to the cavity, thusallowing the etchant to more easily gain access to the sacrificialmaterial. Indeed, the method shown in FIG. 41 can be used without theaddition of an object in order to create structures in which one or moreregions of sacrificial material contain a cavity to improve etching. Inaddition, during a planarization step, it may be advantageous to havethe sacrificial material adjacent to the structural material as shown inFIG. 41( i), such that the structural material may smear less on itscorners.

According to further embodiments of the invention, as shown in FIGS. 42(a)-42(p), the patternable mold material may be used as the sacrificialmaterial in order to form channels or other hollow shapes within layersformed on a substrate. As shown in FIG. 42( a), a substrate 240 isprovided, onto which patternable mold material 242 (for example,photoresist or solder mask) has been deposited as shown in FIG. 42( b).In FIG. 42( c), material 242 has been patterned (for example, if aphotoresist, by use of a photomask, developing, etc., by laser directimaging, a pattern generator and the like or, a combination of thesemethods) to produce apertures 225 and 227 and patternable mold materialportions 242(a) and 242(b). In FIG. 42( d), a structural material 244(for example, a metal such as gold) has been formed (for example byelectrodeposition) in apertures 225, 227. According to some embodiments,planarization may then be performed, if necessary, as shown in FIG. 42(e). In FIG. 42( f), a second layer of patternable mold material 246 hasbeen formed over patternable mold material 242 and structural material244 and patterned as shown in FIG. 42( g). In FIG. 42( h), another layerof structural material 244 has been formed over the first layer ofstructural material 244, by, for example, electrodeposition.

It can be seen in FIG. 42( h) that the second layer of structuralmaterial 244 is formed over the first layer of structural material 244.Structural material 244 also mushrooms over onto the narrow portion242(a) of patternable mold material from both sides (as indicated byreference number 229 in FIG. 42( h)) such that portion 242(a) iscompletely covered by structural material 244. The dimensions of thepatternable mold material 246 that has been patterned to remain overwide portion 242(b), as shown in FIG. 42( h), may be chosen such as tofill a space that it has been predetermined will approximately exist asa result of the mushrooming of structural material 244 over the wideportion 242(b). The amount of mushrooming that may occur for a givendeposited material may be determined based on factors such as, forexample, the thickness of the deposited material, the type of platingbath used, the amount of agitation within the plating bath and otherplating parameters. In FIG. 42( i), planarization has been performed.

In FIG. 42( j), a third layer of patternable mold material 248 has beenformed over the second layer of structural material 244 and patternablemold material 246. Patternable mold material 248 is then patterned. InFIG. 42( k), a third layer of structural material 244 has been formedover the second layer of structural material 244 and patternable moldmaterial 246. Again, the dimensions of the patternable mold material 248that has been patterned to remain over patternable mold material 246, asshown in FIG. 42( k), may be chosen such as to fill a space that it hasbeen predetermined will approximately exist as a result of themushrooming of structural material 244 over patternable mold material246. In FIG. 42( m), planarization has again been performed.

In FIG. 42( n), a fourth layer of structural material 244 has beenformed over the third layer of structural material 244 and patternablemold material 248. The dimensions of the patternable mold material 248that has been patterned to remain over patternable mold material 246 arenow such that mushrooming of structural material 244 from both sides (asindicated by reference number 231 in FIG. 42( n)) completely coverspatternable mold material 248. In FIG. 42( o), planarization has againbeen performed. In FIG. 42( p), the sacrificial patternable moldmaterial has been removed, leaving channels 250 and 252.

As described above, some embodiments of the invention advantageously usea patternable mold material as the sacrificial material to formstructures with only the patternable mold material and a structuralmaterial. In this manner, an additional metal sacrificial material isnot required to build structures. In addition, structures that might bedifficult to etch using a metal sacrificial material are possible whenusing a patternable mold material as the sacrificial material, accordingto some embodiments of the invention as described above. For example, ifthe patternable mold material is a polymer material, etching may beperformed using plasma, which penetrates into narrow cavities moreeasily than a liquid etchant can. According to some embodiments of theinvention, structural material 244 may be the same material on eachlayer or may be two or more different materials. According to someembodiments of the invention, software may be used to automaticallymodify the original geometry so as to allow structures to be fabricatedusing a patternable mold material as the sacrificial material. Forexample, the channel on the right side of FIG. 42( p) may have beenoriginally designed with a rectangular shape similar to the channel onthe right, but wider. In this case the software—having been providedwith information about the maximum width of mold material that may bebridged by mushrooming structural material (as a function of variousparameters)—may have modified the rectangular geometry to yield thedomed geometry shown in FIG. 42( p) to enable fabrication.

FIGS. 43( a)-(r) show an alternative embodiment for using patternablemold material as the sacrificial material. As shown in FIG. 43( a), asubstrate 254 is shown, onto which patternable mold material 256 (forexample, photoresist or solder mask) has been deposited as shown in FIG.43( b). In FIG. 43( c), material 256 has been patterned (for example, ifa photoresist, by use of a photomask, developing, etc., by laser directimaging, a pattern generator and the like or, a combination of thesemethods) to produce apertures 233 and 235. In FIG. 43( d), a material258 (for example, a metal such as copper) has been formed (for exampleby electrodeposition) in apertures 233, 235. In FIG. 43( e),planarization has been performed.

In FIG. 43( f), in order to make the top surface of the patternable moldmaterial 256 conductive, a coating of fine particles 260 are applied tothe top surface of patternable mold material 256. According to someembodiments of the invention, the particles 260 may be applied as aslurry within a liquid carrier such as, but not limited to, alcohol. Thecarrier then evaporates, leaving behind the particles 260. According toalternative embodiments, the particles 260 may be airborne particlesthat are “dusted” onto the surface of material 258 and patternable moldmaterial 256. According to further alternative embodiments, theparticles 260 may be applied onto the surface of material 258 andpatternable mold material 256 using an electrostatic attraction.Particles 260 are chosen such that they do not adhere strongly to thesurface of the material 258 and may easily be washed away or otherwiseremoved. In one embodiment, particles 260 may be, for example, copperparticles.

In FIG. 43( g), patternable mold material 256 has been made softerand/or tackier by, for example, heating and/or through the use of asuitable solvent in order to secure the particles 260 using thepatternable mold material 256. If heating is used, it may be done in anoven, for example, or may be done using infrared light or other suitablemethod of heating. In some embodiments, in addition, or in thealternative, pressure may be applied (for example, with a conformablepad) to the particles 260 in order to push them into the patternablemold material 256. According to still further embodiments, a patternablemold material may be used that has selectively tacky areas for receivingthe particles and other areas that are not tacky and will not receivethe particles.

Then, as shown in FIG. 43( h), a removal process (e.g., a rinse,application of a stream of air and the like) has been performed toremove the particles 260 that are above the material 258, such that theparticles 260 remain only over the patternable mold material 256 whichwas softened and made tackier by the process described above to receiveand secure them. According to some embodiments of the invention, theparticles may be washed away using, for example, alcohol or othersuitable material.

The particles 260 may be applied close enough together that they form acontinuous conductive film over patternable mold material 256 andmaterial 258. In other embodiments, after application of the particles260, they may be consolidated by melting during, for example, a heatingstep. The heating step may be a heating step as described above forsoftening patternable mold material 256.

As a result, as shown in FIG. 43( h), assuming material 258 isconductive (for example, a metal), a completely conductive surface nowexists due to the linking together of portions of material 258 byconductive particles 260. Thus, a plating base exists for plating of asubsequent layer. In some embodiments, small gaps between the particles260 may be acceptable in forming a plating base, as bridging of material258 may occur across the gaps between individual particles 260. In FIG.43( i), a second layer of patternable mold material 262 has been formedover material 258 and particles 260. In FIG. 43( j), patternable moldmaterial 262 has been patterned to form apertures 237, 239 and 241. InFIG. 43( k), a second layer of material 258 has been deposited intoapertures 237, 239 and 241. In FIG. 43( l), planarization may beperformed, if necessary.

In FIG. 43( m), a second layer of particles 260 are applied to the topsurface of the second layer of material 258 and patternable moldmaterial 262 to form a conductive plating base, as described above. InFIG. 43( n), the particles 260 have been secured to patternable moldmaterial 256, as described above. In FIG. 43( e), a removal process hasbeen performed to remove particles 260 that are above the material 258,such that the particles 260 remain only over the patternable moldmaterial 262. In FIG. 43( p), a third layer of patternable mold material264 and a third layer of material 258 have been formed in the samemanner as that described above. Additional layers may be formed in thesame manner if desired.

In FIG. 43( q), patternable mold material 256, 262 and 264 has beenremoved. According to some embodiments of the invention, particles 260may also be a sacrificial material (i.e., may be removed to form a finalstructure). In that case, particles 260 may be removed using anadditional removal step suitable to the material used to form particles260. As shown in FIG. 43( q), particles 260 may be removed by, forexample, a liquid etchant. The liquid etchant may easily access andremove the particles 260 due to the open channels that are formed by theremoval of the patternable mold material. In FIG. 43( r), an exemplaryfinal structure formed from material 258 is shown. According to someembodiments of the invention, material 258 may be the same material oneach layer or may be two or more different materials. In addition, insome embodiments, it may be desirable to leave particles 260 in thefinal structure such that the final structure would be as shown in FIG.43( q).

According to some alternative embodiments of the invention, instead ofapplying particles 260 in the step shown in FIG. 43( f), the particles260 may be applied to exposed areas of patternable mold material 256after the second layer of patternable mold material 262 is formed andpatterned as shown in FIG. 43( j). The particles 260 may then be securedin the patternable mold material 256 using a process as described above.

According to other alternative embodiments of the invention, apatternable mold material may be used to form a pattern for thedeposition of a material such as material 258. After material 258 hasbeen deposited, the patternable mold material may then be removed andreplaced with a tacky material that is suitable for receiving particles260 without an additional heating step or the use of a solvent.According to further alternative embodiments, a patternable moldmaterial may be used to form a pattern for the deposition of a materialsuch as material 258. The patternable mold material may then be removedand replaced with a conductive material other than a metal to form acontinuous plating base with the deposited material. Such a non-metalconductive material (for example, a conductive polymer such as aconductive epoxy) may have the advantage of being more easily removablethan a metal. Particles 260 are preferably small to minimize anypotential roughness (as indicated in FIG. 43( r) on surfaces facingsubstrate 254.

FIGS. 44( a)-(i) show another alternative embodiment for usingpatternable mold material as the sacrificial material. As shown in FIG.44( a), a substrate 266 is shown, onto which patternable mold material268 (for example, photoresist or solder mask) has been deposited asshown in FIG. 43( b). Patternable mold material 268 may be applied, forexample, using a spin-on process, using a curtain coater or any othersuitable method to apply the patternable mold material. Patternable moldmaterial 268 comprises conductive particles 270 that are initiallydispersed at a low density throughout the patternable mold material 268.The low density dispersion of particles 270 allows light to be passedthrough the patternable mold material 268 so that it may be patterned toform apertures 243 and 245 without significant interference fromparticles 270, as shown in FIG. 44( c).

In FIG. 44( d), material 272 has been formed in apertures 243 and 245.In FIG. 44( e), power supply provides an electric field for drivingparticles 270 to the upper surface of patternable mold material 268 toform a plating surface for a subsequent layer of material 272. Anelectrode having one polarity is positioned above an upper surface ofpatternable mold material 268 and substrate 266 serves as an electrodeof opposite polarity such that a resulting electric field drives theconductive particles 270 to the upper surface of the patternable moldmaterial 268.

Other alternative methods for driving particles 270 to the upper surfaceof patternable mold material 268 include, but are not limited to,applying a magnetic field to magnetically attract the particles 270 tothe upper surface of patternable mold material 268; applying acentrifugal force to induce the particles 270 to migrate to the uppersurface of patternable mold material 268; lowering a viscosity of thepatternable mold material 268 such that the particles migrate (e.g., ifbuoyant) to the upper surface of patternable mold material 268; andvibrating the substrate 266 and patternable mold material 268 such thatthe particles 270 to migrate to the upper surface of patternable moldmaterial 268; or any combination of the above.

According to some alternative embodiments of the invention, the drivingof the particles 270 the upper surface of the patternable mold materialmay be performed at times in the process other than as has been alreadydescribed. For example, the driving step may be performed at some pointafter the patternable mold material 268 has been patterned, as shown inFIG. 44( c), but before the second layer of material 272 is deposited,as shown in FIG. 44( h). According to some embodiments of the invention,material 272 may be the same material on each layer or may be two ormore different materials.

In FIG. 44( f), after the particles 270 have been positioned along theupper surface of the patternable mold material 268 to form a platingsurface, a second layer of patternable mold material 278 has been formedand patterned to produce apertures 247 and 249, as shown in FIG. 44( g).In FIG. 44( h), a second layer of material 272 has been formed inapertures 247, 249 and planarized if necessary. In FIG. 44( i),patternable mold material 268, 278 and particles 270 have been removedand a final structure formed from material 272 remains.

In other alternative embodiments, the patternable mold material may beused as a sacrificial material along with two or more structuralmaterials or along with a second sacrificial material. In still otherembodiments, the patternable mold material may be used as one of two ormore structural materials with or without a sacrificial material, or itmay be used as a structural material along with a sacrificial material(e.g. an electrodeposited metal) that will be removed. In still otherembodiments seed layers may be applied in a variety of ways to thepatternable mold material to allow more geometric freedom in terms ofthe structures that can be formed. Various alternative techniques forapplying and removing seed layer materials may be found in U.S. patentapplication Ser. No. 10/841,300, filed May 7, 2004 (Microfabrica DocketNo. P-US099-A-MF) referenced in the table to follow and incorporatedherein by reference. In some embodiments, seed layers may be applied ina planar manner and as necessary undesired portions may be removed afterpatterning a desired material on the seed layer. In some embodimentsseed layers may be applied in a selective or blanket manner (e.g. anon-planar manner) over an initially applied dielectric or conductivematerial so it is only located on desired portions of a previouslyformed layer and such that planarization operations may be used toremove it from undesired regions (e.g. above the dielectric orpreviously applied conductive material). In still other embodiments, acombination of these approaches may appropriate.

FIGS. 45( a)-(m) show an embodiment of the invention for building layerson large substrates in such a manner as to minimize stresses to a largesubstrate that may result from deposited materials (which may be exhibitresidual stress) deforming the substrate, causing cracking of depositedmaterials, separation between deposited materials, and so forth.Stresses due to thermal expansion of deposited materials as a result ofheating or cooling the deposited materials and/or substrate (thedeposited materials may have different coefficients of thermalexpansion) can also be minimized by some embodiments of the invention.In addition, some embodiments of the invention may facilitate dicing oflarge substrates into smaller pieces.

According to exemplary EFAB processes, a selective deposition of a firstmaterial is performed. Then a blanket deposition of a second material isperformed. Thus, if a wafer including many devices is being fabricated,the devices are usually constructed of a structural material confined toparticular dies on the wafer. Sacrificial material would then be blanketdeposited everywhere else on the wafer. This ‘ocean’ of sacrificialmaterial may mechanically couple together all the devices. Any stressesthat may be associated with the sacrificial or structural material maythus be disadvantageously coupled across the entire wafer and may cause,for example, cracking of the deposited materials and/or distortion (suchas bowing) of the wafer.

In order to minimize such problems, some embodiments of the inventionrestrict the area where the sacrificial material is deposited by formingregions free of sacrificial material during the fabrication process anddoing a second pattern deposit of the material rather than a blanketdeposit. In this manner, the sacrificial material is only placed whereit is needed and any cracking, bowing or other distortion of the waferis minimized. These regions may correspond to the dicing lanes betweenindividual die, as is assumed in the description shown in FIG. 45, ormay be formed in any other pattern as required.

As shown in FIG. 45( a), a substrate 280 is shown, onto whichpatternable mold material 282 (for example, photoresist or solder mask)has been deposited as shown in FIG. 45( b). In FIG. 45( c), material 282has been patterned (for example, if a photoresist, by use of aphotomask, developing, etc., by laser direct imaging, a patterngenerator and the like or, a combination of these methods) to produceapertures 251, 253, 255, 257, 259 and 261 between portions ofpatternable mold material 282(a) and 282(b) that will later be removedto form dicing lanes. Apertures 251 and 253 belong to a first die on thesubstrate. Apertures 255 and 257 belong to a second die on thesubstrate. Apertures 259 and 261 belong to a third die on the substrate.In FIG. 45( d), a first material 284 (for example, a metal such asnickel) has been selectively formed (for example by electrodeposition)in apertures 251, 253, 255, 257, 259 and 261 and planarization, ifnecessary, has been performed.

In FIG. 45( e), patternable mold material 282 has been removed anddicing lanes 263 and 265 are formed. In FIG. 45( f), a second layer ofpatternable mold material 286 has been deposited over material 282.Patternable mold material 286 may be, for example, a dry film resist, aliquid resist, or any other suitable patternable mold material. In FIG.45( g), patternable mold material 286 has been patterned to formprotective barriers over dicing lanes 263 and 265 that are locatedbetween the three dies. A dry film resist may tent over apertures 255and 257, as shown in FIG. 45( g). If a liquid or electrodeposited resistis used, it may fill apertures 255 and 257. According to someembodiments of the invention In FIG. 45( h), a second material 288 hasbeen deposited over exposed portions of first material 284 and substrate280. In FIG. 45( i), patternable mold material 286 has been removed. InFIG. 45( j), planarization has been performed. It can be seen in FIG.45( j) that dicing lanes 263, 265 are not filled with second material288.

According to some alternative embodiments of the invention, patternablemold material 286 may be removed during the planarization step ratherthan in a separate step. Where a liquid resist is used, a portion of theresist left in apertures 255 and 257 after planarization may remainduring the build process (though it may ultimately be removed). Thepatternable mold material filling apertures 255 and 257 may bebeneficial during the planarization process for, as an example,minimizing smearing of the metals.

In FIG. 45( k), three layers of first material 284 and second material288 have been built on substrate 280 in the manner described above. InFIG. 45( l), dicing of substrate 280 has been performed. It can be seenfrom FIG. 45( l) that the dicing may be performed without having to cutthrough the first and second materials. This may be beneficial in thatdeposited metals have a tendency to negatively affect tools such asdicing saws that are used to perform the dicing (e.g., clogging the sawblade due to their relative softness), whereas the substrate may not doso. In FIG. 45( m), the first material 284 has been removed, leaving astructure formed from the second material 288.

Thus, it can be seen that some embodiments of the invention as describedabove may minimize deleterious effects such as cracking and distortion.Because the dicing lanes of the substrate do not receive the secondmaterial when it is deposited, individual dies are de-coupled from eachother and stresses on the substrate are minimized. According to somealternative embodiments of the invention, if the die layout of aparticular substrate is known a generic mask (such as a conformablecontact mask) for masking out the dicing lanes may be used to preventdeposition into the dicing lanes.

Arrays of structures are often fabricated to fulfill a particularfunction. For example, an array of probe tips may be desirable forprobing a wafer. As a result, a set of photomasks may be created topattern a first array of probes on a first wafer having particulardevices at particular locations on the first wafer. If a second waferhas devices located at different locations than the first wafer, it maybe necessary to create a new set of photomasks for patterning a newarray of probes suitable for the second wafer. Thus, it may be requiredto create a new set of photomasks for patterning an array of devicessuch as probes each time the layout of the probes changes.

FIGS. 46( a)-(q) show an embodiment of the invention for fabricatingcustomized arrays of devices without needing to use an entirely new setof photomasks for each customized array configuration. Instead,according to some embodiments of the invention, a first set ofphotomasks may be used to create a full array of structures that may beused with many different device layouts. Depending on a particulardevice layout, a second photomask may be used to select particular onesof the structures in the full array that will be removed from the fullarray in order to form a “customized array”. According to someembodiments of the invention, the structures selected for removal fromthe full array may be removed during the fabrication process by creatinga delamination condition for the selected structures. In this manner,rather than creating a new set of photomasks having a new desired arrayof structures, only one new photomask is required.

As shown in FIG. 46( a), a substrate 290 is shown, onto which positivepatternable mold material 292 (for example, a positive photoresist) hasbeen deposited as shown in FIG. 46( b). In FIG. 46( c), photomask 294 isused to expose patternable mold material 292 in a manner that wouldpattern a full array of five sets of portions of the patternable moldmaterial that would be used to form five devices if no additionalexposures of the patternable mold material 292 were to occur (See FIG.46( e)). The number of devices has been arbitrarily chosen to be fivefor simplicity. Some embodiments of the invention are also applicable toarrays having different numbers of devices.

According to some embodiments of the invention, in FIG. 46( d), a secondphotomask 296 is used to again expose patternable mold material 292 suchthat two of the five sets of portions of the patternable mold materialthat would result from the first exposure with photomask 294 will not beformed. (According to other embodiments, the sequence of exposure by thefirst and second photomasks may be reversed.) In FIG. 46( e), thepattern of the array of devices is shown. It can be seen in FIG. 46( e)that only three of the five sets of portions of the patternable moldmaterial have been patterned. Two of the sets (shown by phantom lines)have not been patterned as a result of the second exposure of thepatternable mold material 292 using photomask 296. In FIG. 46( f), firstmaterial 298 (for example, nickel) has been formed in aperturesresulting from the patterning of patternable mold material 292. In FIG.46( g), patternable mold material 292 has been removed. In FIG. 46( h),a second material 302 (for example, copper) has been blanket depositedover exposed portions of substrate 290 and first material 298. In FIG.46( i), planarization has been performed.

In FIG. 46( j), a second layer of positive patternable mold material 304is formed over first material 298 and second material 302. As shown inFIG. 46( k), photomask 306 is used to pattern patternable mold material304 in order to form an array of five devices. According to theexemplary embodiment, a second masking step is not performed on thesecond layer of devices, as was done on the first layer. However,according to other embodiments such a second masking step may beperformed with a custom photomask if desired. In FIG. 46( l), a secondlayer of first material 298 has been formed in the apertures that havebeen patterned in patternable mold material 304 and a planarization stephas been performed if necessary. In FIG. 46( m), patternable moldmaterial 304 has been removed. In FIG. 46( n), a second layer of secondmaterial 302 has been formed and planarization has been performed. InFIG. 46( o), two additional layers of first material 298 and secondmaterial 302 have been formed in the same manner.

In FIG. 46( p), first material 298 has been removed, including portionson which the two devices patterned for removal during the secondexposure step (shown in FIG. 46( d)) have been formed. Because theportions of first material 298 supporting these two devices are removed,the devices themselves will also be separated from substrate 290, asshown. In FIG. 46( q), an array of devices having a selectedconfiguration has been formed.

FIGS. 47( a)-(j) show another embodiment of the invention forfabricating customized arrays of devices without needing to use adifferent set of photomasks for each customized array configuration. Theembodiment described below differs from the embodiment previouslydescribed in that a negative patternable mold material is used ratherthan a positive patternable mold material. Also, in the embodimentdescribed below the structural material is deposited first and thesacrificial material is deposited second, whereas the reverse was truefor the previously described embodiment.

As shown in FIG. 47( a), a substrate 308 is shown, onto which a negativepatternable mold material 310 (for example, a negative photoresist) hasbeen deposited as shown in FIG. 47( b). In FIG. 47( c), photomask 312 isused to expose patternable mold material 310 to form sets of aperturesfor forming a full array of five devices. Again, some embodiments of theinvention are applicable to arrays having any number of devices. In FIG.47( d), a second photomask 314 is used to again expose patternable moldmaterial 310 such that two of the sets of apertures (shown by phantomlines in FIG. 47( e)) will not be formed. In FIG. 47( f), a firstmaterial 316 (e.g., nickel) has been formed in the apertures patternedin patternable mold material 310 and planarization has been performed ifnecessary. In FIG. 47( g), patternable mold material 310 has beenremoved. In FIG. 47( h), a second material 318 (e.g., copper) has beenblanket deposited over exposed portions of substrate 308 and firstmaterial 316. In FIG. 47( i), planarization has been performed. In FIG.47( j), a second layer of negative patternable mold material 320 hasbeen deposited. As shown in FIG. 47( k), photomask 322 is used topattern patternable mold material 320 in order to form an array of fivedevices. According to the exemplary embodiment, a second masking step isnot performed on the second layer of devices, as was done on the firstlayer. However, according to other embodiments such a second maskingstep may be performed with a custom photomask if desired. In FIG. 47(l), a second layer of first material 316 has been formed in theapertures that have been patterned in patternable mold material 320 anda planarization step has been performed if necessary. In FIG. 47( m),patternable mold material 320 has been removed. In FIG. 47( n), a secondlayer of second material 318 has been formed and planarization has beenperformed. In FIG. 47( o), two additional layers of first material 316and second material 318 have been formed in the same manner.

In FIG. 47( p), second material 318 has been removed, including portionson which the two devices patterned for removal during the secondexposure step (shown in FIG. 47( d)) have been formed. Because theportions of second material 318 supporting these two devices areremoved, the devices themselves will also be separated from substrate290, as shown. In FIG. 47( q), an array of devices having a selectedconfiguration has been formed.

Thus, according to some embodiments of the invention, a first set ofphotomasks is used to fabricate a full array of structures. A secondphotomask is then used to selectively remove particular ones of thestructures from the full array by creating a delamination condition forthe selected structures by forming the selected structures on asacrificial material that will be removed from the substrate. When thesacrificial material is removed, the selected structures are removedfrom the full array of structures.

According to some alternative embodiments of the invention, rather thandouble exposing the patternable mold material, a simultaneous exposuremay be performed in which one or more photomasks of the set used tofabricate a full array of structures is exposed in series with a secondphotomask. In this case, the two masks may be aligned to each other aswell as to the substrate. To do this, one mask may be put into the maskaligner (not shown) as is normally done. The other mask may then be putonto the substrate chuck (not shown) in order to align the two maskswith one another. The two masks may be put in contact with one anotherand then clamped in the mask aligner. According to yet other alternativeembodiments of the invention, in lieu of a double exposure orsimultaneous exposure using two photomasks to pattern the mold materialfor a given layer of a group of structures, a single customizedphotomask may be used to pattern a patternable mold material wherein thesingle photomask is used to pattern only the desired configuration ofdevices, again creating a delamination condition for selectedstructures.

FIG. 48( a) shows a substrate 324 on which a structural material 326 anda sacrificial material 328 have been formed. As shown in FIG. 48( b),when the sacrificial material 328 is removed, the remaining structuralmaterial 326 forms structures having a certain length l. According tosome embodiments of the invention described above for fabricatingcustomized arrays of devices, an interruption at a particular length inselected ones of the structures may be brought about through the use ofthe methods described above for creating customized arrays of devices.

FIG. 49( a) shows a substrate 324 on which a structural material 326 anda sacrificial material 328 have been formed. According to someembodiments of the invention, interruptions are formed in the structuralmaterial using one or more of the methods described above for creatingcustomized arrays of devices. As shown in FIG. 49( a), a first group ofinterruptions 267 is formed by patterning a first layer using eitherdouble exposure with two masks, simultaneous exposure with two masks, ora single mask customized for the layer, as described above. Then asecond group of interruptions 269 is formed by patterning a second layerusing one of the methods described above. Finally, a third group ofinterruptions 271 is formed by patterning a third layer using one of themethods described above. In FIG. 49( b), sacrificial material 328 hasbeen removed, leaving behind structures of material 326 having varyinglengths.

According to the embodiment of the invention shown in FIGS. 49( a)-(b),the portions of the structures that are removed may be discarded ifattachment to a substrate is required for usability. According to analternative embodiment shown in FIGS. 50( a)-(d), the portions removedmay be preserved. FIG. 50( a) shows a substrate 324 on which astructural material 326 and a sacrificial material 328 have been formed.Interruptions are formed in the structural material using one or more ofthe methods described above for creating customized arrays of devices.As shown in FIG. 50( a), a first group of interruptions 273 is formed bypatterning a first layer using either double exposure with two masks,simultaneous exposure with two masks, or a single mask customized forthe layer, as described above. Then a second group of interruptions 275is formed by patterning a second layer using one of the methodsdescribed above.

In FIG. 50( b), a second substrate 330 is added on a side of the buildof layers opposite from the substrate 324 before sacrificial material328 is removed. In FIG. 50( c), substrate 324 is shown after removal ofsacrificial material 328 and has structures of varying length. In FIG.50( d), substrate 330 is shown after removal of sacrificial material 328and has structures of varying length. The structures on substrate 330are complementary to those on substrate 324.

According to some embodiments of the invention shown in FIGS. 51(a)-(b), a tie may be formed in the structural material to hold togetherthe portions of the structural material that are removed. FIG. 51( a)shows a substrate 332 on which a structural material 326 and asacrificial material 328 have been formed. According to some embodimentsof the invention, a tie 334 is formed in at least one layer (e.g., afinal layer as shown here) of the build of layers such that when thesacrificial material 328 is removed as shown in FIG. 51( b), the tie 334holds together what would have otherwise been individual portions of thestructural material 326. This may be advantageous in preventingindividual portions of the removed structural material 326 from becomingtangled with portions remaining on substrate 332 during the process forremoving the sacrificial material 328. A chuck such as a vacuum chuck ora magnetic chuck may be attached to the tie 334 either before or afterremoval of sacrificial material 328 in order to pull away the removedstructural material 326.

FIGS. 52( a)-(g) show an embodiment of the invention for pre-patterninga patternable mold material on a temporary substrate before using thetemporary substrate to form a pattern for depositing other materials ona separate substrate. FIG. 52( a) shows temporary substrate 336.Patternable mold material 338 is formed on temporary substrate 336, asshown in FIG. 52( b). In FIG. 52( c), patternable mold material 338 hasbeen patterned. In FIG. 52( d), temporary substrate 336 and patternablemold material 338 have been turned over and bonded (for example, byadhesion or re-lamination) to a separate substrate 340. In FIG. 52( e),temporary substrate 336 has been removed (e.g., by peeling off ordissolving). In FIG. 52( f), material 342 is formed in aperturesresulting from the patterning of patternable mold material 338. In FIG.52( g), patternable mold material 338 has been removed.

Thus, according to the above-described embodiment, a pattern may betransferred from a temporary substrate to a substrate on which layerswill be built by temporarily bonding a patternable mold material to thetemporary substrate and then bonding the patternable mold material tothe build substrate and removing the temporary substrate. According tosome embodiments of the invention, the patternable mold material may bea dry film resist that will mechanically interlock with and/orchemically bond with a surface of the temporary substrate and the buildsubstrate. The temporary substrate may be chosen such that it does nothave good adhesion properties with respect to the patternable moldmaterial used. The temporary substrate may be, for example, Teflon®,SYTOP® or polypropylene or may be a sacrificial material that may bedissolved. According to embodiments wherein the patternable moldmaterial is a dry film resist, the backing material of the dry filmresist may be adhered to the temporary substrate or may serve as thetemporary substrate while the dry film resist is exposed and developed.Then, the backing may be removed, along with any additional temporarysubstrate used.

FIGS. 53( a)-(f) show another embodiment of the invention fortransferring a pattern from a temporary substrate to a build substrate.FIG. 53( a) shows temporary substrate 344. Temporary substrate 344 is apermeable substrate. Patternable mold material 346 is formed ontemporary substrate 344, as shown in FIG. 53( b). In FIG. 53( c),patternable mold material 346 has been patterned. In FIG. 53( d),temporary substrate 344 and patternable mold material 346 have beenturned over and bonded (for example, by adhesion or re-lamination) to abuild substrate 348. In FIG. 53( e), material 350 has been formedthrough permeable temporary substrate 344 in apertures resulting fromthe patterning of patternable mold material 346. As shown in FIG. 53(e), according to some embodiments, material 350 may not completely fillthe apertures in order to avoid welding the material 350 to thetemporary substrate 344. In FIG. 53( f), temporary substrate 344 hasbeen removed by dissolving or otherwise removing patternable moldmaterial 346. The patternable mold material 346 may be removed, forexample, by a stripper that passes through the permeable temporarysubstrate 344.

FIGS. 54( a)-(f) show another embodiment of the invention fortransferring a pattern from a temporary substrate to a build substrate.FIG. 54( a) shows temporary substrate 352. Temporary substrate 352 maybe a sacrificial anode formed from, for example, solid copper, or mayhave a coating of material such as copper. Patternable mold material 354is formed on temporary substrate 352, as shown in FIG. 54( b). In FIG.54( c), patternable mold material 354 has been patterned. In FIG. 54(d), temporary substrate 352 and patternable mold material 354 have beenturned over and bonded (for example, by adhesion or re-lamination) to abuild substrate 356.

In FIG. 54( e), material 358 has been formed in apertures resulting fromthe patterning of patternable mold material 354 during a plating stepwherein the temporary substrate 352 and build substrate 356 may beimmersed in an electrodeposition tank (not shown) during a plating step.Material 358 is formed from the erosion of temporary substrate 352during the plating step, as shown in FIG. 54( e). In FIG. 54( f),temporary substrate 352 has been removed after the plating step byremoving patternable mold material 354. The patternable mold material354 may be dissolved, for example, by a stripper applied to the sides ofthe build. According to alternative embodiments, temporary substrate 352may be removed during a planarization step.

FIGS. 55( a)-(i) show an embodiment of the invention for depositing morethan one material in an aperture formed in a patternable mold materialsuch that a layered deposit of materials are formed on a single layer.

As shown in FIG. 55( a), a substrate 360 is shown, onto whichpatternable mold material 362 (for example, photoresist or solder mask)has been deposited as shown in FIG. 55( b). In FIG. 55( c), material 362has been patterned (for example, if a photoresist, by use of aphotomask, developing, etc., by laser direct imaging, a patterngenerator and the like or, a combination of these methods) to produceapertures. In FIG. 55( d), a first material 364 is formed in theapertures resulting from the patterning step. In FIG. 55( e), a secondmaterial 368 is formed in the apertures over the first material 364. InFIG. 55( f), patternable mold material 362 has been removed. In FIG. 55(g), third material 366 is blanket deposited over exposed areas ofsubstrate 360, first material 364 and second material 368. In FIG. 55(h), planarization has been performed.

According to some embodiments of the invention, first material 364 maybe a soft material (for example, tin), while second material 368 may bea material that is harder than first material 364 (for example, nickel).In this manner, some embodiments of the invention allow a planarizationstep to be performed such that the second material 368 is planarizeduntil just before the first material 364 is reached, as shown in FIG.55( h). This advantageously allows the use of a softer material as thefirst material. The softer material will not be subjected to the rigorsof planarization (which may lead to excessive smearing of the softermaterial, inclusions of abrasive, etc.) because it is coated with aharder material such that the harder material is planarized and not thesofter material. After planarization, an etching step, for example, maybe used to remove the remainder of the harder material, as shown in FIG.55( i), leaving the softer material unexposed to planarization.

Although two materials are shown as being formed in the apertures inFIG. 55( e), some embodiments of the invention are equally applicable toforming any number of materials in the apertures before the patternablemold material is removed. Other applications for some embodiments of theinvention for depositing more than one material in an aperture formed ina patternable mold material include, but are not limited to, formingdevices having a superlattice of different materials, and forming alloysby using heat to inter-diffuse multiple materials deposited one abovethe above.

FIGS. 56( a)-(i) show an alternative embodiment of the invention fordepositing more than one material in an aperture formed in a patternablemold material such that a layered deposit of materials are formed on asingle layer. According to some embodiments of the invention, a firstmaterial may be deposited into an aperture and may have a top surfacehaving a geometric shape or particular composition or microstructurewhich it is desirable to preserve during subsequent fabricationprocesses. Thus, a second material may be deposited into the aperture tocoat the first material and preserve the shape or composition of thefirst material during subsequent fabrication processes.

As shown in FIG. 56( a), a substrate 370 is shown, onto whichpatternable mold material 362 (for example, photoresist or solder mask)has been deposited as shown in FIG. 56( b). In FIG. 56( c), material 372has been patterned (for example, if a photoresist, by use of aphotomask, developing, etc., by laser direct imaging, a patterngenerator and the like or, a combination of these methods) to produceapertures. In FIG. 56( d), a first material 374 is formed in theapertures resulting from the patterning step. It is assumed that firstmaterial 374 has a top surface that it is desirable to preserve for somereason, for example, one of the reasons discussed above. Therefore, inFIG. 56( e), a second material 376 is formed in the apertures over thefirst material 374. In FIG. 56( f), patternable mold material 372 hasbeen removed. In FIG. 56( g), third material 378 is blanket depositedover exposed areas of substrate 370, first material 374 and secondmaterial 376. In FIG. 56( h), planarization has been performed. In FIG.56( i), second material 376 has been removed, again exposing the firstmaterial 374 after the planarization step.

FIGS. 57( a)-(g) show an embodiment of the invention that uses apatternable mold material to perform a patterned etch. FIG. 57( a) showsthree layers of two materials 384, 386 built on a substrate 380. Theuppermost layer of the build is shown thicker than the first two layersbecause planarization has not yet been performed on the uppermost layer.In FIG. 57( b), patternable mold material 382 has been formed over theuppermost layer of the build. In FIG. 57( c), patternable mold material382 has been patterned to form apertures. In FIG. 57( d), the aperturesare used for etching cavities into a previously deposited material,which may be a sacrificial material or a structural material. In FIG.57( e), the cavities are filled with a third material 388. In FIG. 57(f), patternable mold material 382 has been removed. In FIG. 57( g),planarization has been performed, if necessary.

Thus, some embodiments of the invention as described above may be usedto perform a patterned etch of an existing material on a layer such thatanother material may be added to the layer. As shown in FIGS. 57(d)-(e), the patternable mold material 382 may be used both to etch thecavities and to define the deposition of the third material 388, whichminimizes the amount of third material 388 that must be removed duringplanarization. According to other embodiments of the invention,patternable mold material 382 may be removed after the etching step. Ifelectrodeposition is used to deposit the third material 388, any of thethird material 388 formed above the upper level of the cavities may beremoved in during planarization.

FIGS. 58( a)-(j) show an embodiment of the invention for using apatternable mold material both to etch a pattern in a first material andto plate a second material in the etched pattern.

As shown in FIG. 58( a), a substrate 390 is shown, onto which a firstmaterial 392 has been deposited as shown in FIG. 58( b). In FIG. 58( c),a patternable mold material 394 (for example a photoresist) has beendeposited. In FIG. 58( d), material 394 has been patterned (for example,if a photoresist, by use of a photomask, developing, etc., by laserdirect imaging, a pattern generator and the like or, a combination ofthese methods) to produce apertures. In FIG. 58( e), the apertures areused to etch first material 392, as shown. In FIG. 58( f), a secondmaterial 396 is formed in the cavities that have been etched in firstmaterial 392. Again, the patternable mold material may be used both toetch the cavities and to define the deposition of the third material soas to minimize the amount of third material that must be removed duringplanarization. In FIG. 58( g), patternable mold material 394 has beenremoved. In FIG. 58( h), planarization has been performed, if necessary.

It will be understood by those of skill in the art or will be readilyascertainable by them that various additional operations may be added tothe processes set forth herein. For example, between performances of thevarious deposition operations, the various etching operations, andvarious planarization operations cleaning operations, activationoperations, and the like may be desirable.

The patent applications and patents set forth below are herebyincorporated by reference herein as if set forth in full. The teachingsin these incorporated applications can be combined with the teachings ofthe instant application in many ways: For example, enhanced methods ofproducing structures may be derived from some combinations of teachings,enhanced structures may be obtainable, enhanced apparatus may bederived, and the like.

US Pat App No, Filing Date US App Pub No, Pub Date Inventor, Title09/493,496-Jan. 28, 2000 Cohen, “Method For Electrochemical Fabrication”PAT 6,790,377-Sep. 14, 2004 10/677,556-Oct. 1, 2003 Cohen, “MonolithicStructures Including Alignment and/or 2004-0134772-Jul. 15, 2004Retention Fixtures for Accepting Components” 10/830,262-Apr. 21, 2004Cohen, “Methods of Reducing Interlayer Discontinuities in2004-0251142A-Dec. 16, 2004 Electrochemically FabricatedThree-Dimensional Structures” PAT 7,198,704-Apr. 3, 2007 10/271,574-Oct.15, 2002 Cohen, “Methods of and Apparatus for Making High Aspect2003-0127336A-Jul. 10, 2003 Ratio Microelectromechanical Structures” PAT7,288,178-Oct. 30, 2007 10/697,597-Dec. 20, 2002 Lockard, “EFAB Methodsand Apparatus Including Spray 2004-0146650A-Jul. 29, 2004 Metal orPowder Coating Processes” 10/677,498-Oct. 1, 2003 Cohen, “Multi-cellMasks and Methods and Apparatus for 2004-0134788-Jul. 15, 2004 UsingSuch Masks To Form Three-Dimensional Structures” PAT 7,235,166-Jun. 26,2007 10/724,513-Nov. 26, 2003 Cohen, “Non-Conformable Masks and Methodsand 2004-0147124-Jul. 29, 2004 Apparatus for Forming Three-DimensionalStructures” PAT 7,368,044-May 6, 2008 10/607,931-Jun. 27, 2003 Brown,“Miniature RF and Microwave Components and 2004-0140862-Jul. 22, 2004Methods for Fabricating Such Components” PAT 7,239,219-Jul. 3, 200710/841,100-May 7, 2004 Cohen, “Electrochemical Fabrication MethodsIncluding Use 2005-0032362-Feb. 10, 2005 of Surface Treatments to ReduceOverplating and/or PAT 7,109,118-Sep. 19, 2006 Planarization DuringFormation of Multi-layer Three- Dimensional Structures” 10/387,958-Mar.13, 2003 Cohen, “Electrochemical Fabrication Method and2003-022168A-Dec. 4, 2003 Application for Producing Three-DimensionalStructures Having Improved Surface Finish” 10/434,494-May 7, 2003 Zhang,“Methods and Apparatus for Monitoring Deposition 2004-0000489A-Jan. 1,2004 Quality During Conformable Contact Mask Plating Operations”10/434,289-May 7, 2003 Zhang, “Conformable Contact Masking Methods and20040065555A-Apr. 8, 2004 Apparatus Utilizing In Situ CathodicActivation of a Substrate” 10/434,294-May 7, 2003 Zhang,“Electrochemical Fabrication Methods With 2004-0065550A-Apr. 8, 2004Enhanced Post Deposition Processing” 10/434,295-May 7, 2003 Cohen,“Method of and Apparatus for Forming Three- 2004-0004001A-Jan. 8, 2004Dimensional Structures Integral With Semiconductor Based Circuitry”10/434,315-May 7, 2003 Bang, “Methods of and Apparatus for MoldingStructures 2003-0234179 A-Dec. 25, 2003 Using Sacrificial MetalPatterns” PAT 7,229,542-Jun. 12, 2007 10/434,103-May 7, 2004 Cohen,“Electrochemically Fabricated Hermetically Sealed 2004-0020782A-Feb. 5,2004 Microstructures and Methods of and Apparatus for PAT 7,160,429-Jan.9, 2007 Producing Such Structures” 10/841,006-May 7, 2004 Thompson,“Electrochemically Fabricated Structures Having 2005-0067292-May 31,2005 Dielectric or Active Bases and Methods of and Apparatus forProducing Such Structures” 10/434,519-May 7, 2003 Smalley, “Methods ofand Apparatus for Electrochemically 2004-0007470A-Jan. 15, 2004Fabricating Structures Via Interlaced Layers or Via Selective PAT7,252,861-Aug. 7, 2007 Etching and Filling of Voids” 10/724,515-Nov. 26,2003 Cohen, “Method for Electrochemically Forming Structures2004-0182716-Sep. 23, 2004 Including Non-Parallel Mating of ContactMasks and PAT 7,291,254-Nov. 6, 2007 Substrates” 10/841,347-May 7, 2004Cohen, “Multi-step Release Method for Electrochemically2005-0072681-Apr. 7, 2005 Fabricated Structures” 60/533,947-Dec. 31,2003 Kumar, “Probe Arrays and Method for Making” 10/841,300-May 7, 2004Cohen, “Methods for Electrochemically Fabricating 2005 0032375-Feb. 10,2005 Structures Using Adhered Masks, Incorporating Dielectric Sheets,and/or Seed layers That Are Partially Removed Via Planarization”60/534,183-Dec. 31, 2003 Cohen, “Method and Apparatus for MaintainingParallelism of Layers and/or Achieving Desired Thicknesses of LayersDuring the Electrochemical Fabrication of Structures” 11/733,195-Apr. 9,2007 Kumar, “Methods of Forming Three-Dimensional Structures2008-0050524-Feb. 28, 2008 Having Reduced Stress and/or Curvature”11/506,586-Aug. 8, 2006 Cohen, “Mesoscale and Microscale DeviceFabrication 2007-0039828-Feb. 22, 2007 Methods Using Split Structuresand Alignment Elements” PAT 7,611,616-Nov. 3, 2009 10/949,744-Sep. 24,2004 Lockard, “Three-Dimensional Structures Having Feature 2005-0126916Jun. 16, 2005 Sizes Smaller Than a Minimum Feature Size and Methods PAT7,498,714-Mar. 3, 2009 for Fabricating”

Various other embodiments exist. Some of these embodiments may be basedon a combination of the teachings herein with various teachingsincorporated herein by reference. Some embodiments may not use anyblanket deposition process and/or they may not use a planarizationprocess. Some embodiments may involve the selective deposition of aplurality of different materials on a single layer or on differentlayers. Some embodiments may use blanket depositions processes that arenot electrodeposition processes. Some embodiments may use selectivedeposition processes on some layers that are not even electrodepositionprocesses. Some embodiments may use one or more structural materials(for example nickel, gold, copper, or silver). Still other processes mayuse other materials whether or not electrodepositable. Some processesmay use one or more sacrificial materials (for example copper). Someembodiments may use copper as the structural material with or without asacrificial material. Some embodiments may remove a sacrificial materialwhile other embodiments may not. Some embodiments may use conformablecontact masks with different patterns so as to deposit differentselective patterns of material on different layers and/or on differentportions of a single layer.

In view of the teachings herein, many further embodiments, alternativesin design and uses are possible and will be apparent to those of skillin the art. As such, it is not intended that the invention be limited tothe particular illustrative embodiments, alternatives, and usesdescribed above but instead that it be solely limited by the claimspresented hereafter.

1. A method for forming an alignment target on a substrate, comprising:forming a first patternable mold material on the substrate; patterningthe first patternable mold material to form a first aperture; forming afirst material in the first aperture to form an alignment target withinthe first aperture; removing the first patternable mold material;forming a second patternable mold material on the substrate so as tocover the alignment target; and forming the second patternable moldmaterial to form a second aperture wider than and fully enclosing thealignment target.
 2. The method of claim 1, further comprising forming anon-conductive material in the second aperture such that the alignmenttarget is enclosed in the non-conductive material.
 3. The method ofclaim 2, further comprising forming a non-adherent material over thenon-conductive material.
 4. The method of claim 1, wherein forming thefirst material in the aperture comprises forming the first material byelectrodeposition.
 5. The method of claim 2, wherein forming thenon-conductive material comprises forming the non-conductive material byelectrodeposition.
 6. The method of claim 3, wherein forming thenon-adherent material comprises forming the non-adherent material byelectrodeposition.
 7. The method of claim 2, wherein forming thenon-conductive material comprises forming the non-conductive material byblanket depositing and etching the non-conductive material.
 8. Themethod of claim 3, wherein forming the non-adherent material comprisesforming the non-adherent material by depositing and etching thenon-adherent material.
 9. The method of claim 2, wherein forming thefirst material in the aperture comprises forming the first material byelectrodeposition.
 10. The method of claim 2, wherein forming the firstmaterial in the aperture comprises forming the first material bydepositing and etching the non-adherent material.
 11. A method forelectroplating a layer of material on a substrate, comprising: forming aconductive layer over a non-conductive surface of the substrate; forminga target in the conductive layer such that the target is electricallyisolated from the remainder of the conductive layer by thenon-conductive surface of the substrate; and electroplating the layer ofmaterial over the conductive layer such that the conductive layer isplated and the target is un-plated.
 12. A method for patterning odd andeven layers of patternable material formed sequentially on a substrate,comprising: patterning the odd layers using first photomasks having afirst layout of alignment shapes and new target shapes, the first layouthaving a first orientation relative to the substrate; and patterning theeven layers using second photomasks having a second layout of alignmentshapes and new target shapes, the second layout having a secondorientation relative to the substrate different from the firstorientation.
 13. The method of claim 12, wherein the second orientationis 180 degrees opposite the first orientation.